Speed is simply how fast a character can move in a given amount of time. There are five types of speed used for VS purposes: Attack Speed, Combat Speed, Reaction Speed, Travel Speed, and Flight Speed. The term "Speed" normally refers to Combat Speed.
The speed at which an attack moves. For example, X character is hypersonic, but he can do an attack that is a natural beam of light, the speed for the attack is different from the speed of the user, hence the attack would be lightspeed even if its user isn't.
The speed at which a character can fight.
Reaction speed is the speed at which a character can react to an event or action. This usually only grants a short movement upon reaction, whereas several movements at the same speed switch it to combat speed.
For example, say that character A shoots at character B with a gun and character B dodges. That is reaction speed. Keep in mind, sometimes a person aim dodges and it is not as good of a feat.
As another example, let's say that character A uses a minigun on character B, but the minigun takes a second or two to charge up and Character B sees this. If Character B dodges it is considered aim dodging since he/she knew that the attack was going to happen.
Reaction speed is reacting to an attack that you don't know is going to happen, or at a very close range. The reaction speed of a character also tends to be higher than its movement speed.
The speed at which a character or object can move by running, or through similar means that do not involve flight or teleportation.
The speed at which a character or object flies a certain distance, like going from the earth to the sun for example.
High flight speed logically requires similar reaction speed in order to manoeuvre when approaching different objects.
However, certain franchises, such as Marvel Comics (and DC Comics or Image Comics, which follow the same conventions), make a great distinction between regular movement speed and flight speed.
As such, we have generally assumed that the characters' regular reaction or combat speeds are roughly equivalent to their flight speeds, unless this is clearly contradicted.
You can use this calculator to convert from one speed unit to another.
There is also this calculator that you can use for ease of finding how fast your character is (in terms of time, speed, and distance) made to be depending what speed feat they've done. There you can also pretty much get the result of the speed, time, and/or distance your character managed to cover when getting to their destination, what attack or thing they reacted to, and so on.
There is this calculator that one can use to find the KE of a person or object going at Relativistic speeds (as well as other factors involving with it like time dilation and relativistic mass.). Read here when attempting to use this calculator type.
Below Average Human (0-5 m/s)
Normal Human (5-7.7 m/s)
Athletic Human (7.7-9.8 m/s)
Peak Human (9.8-12.43 m/s)
Superhuman (12.43-34.3 m/s)
Subsonic (Faster than Eye) (Mach 0.1-0.5) (34.3-171.5 m/s or 76.7-383.6 mph)
Subsonic+ (Mach 0.5-0.9) (171.5-308.7 m/s)
Transonic (Mach 0.9-1.1) (308.7-377.3 m/s)
Supersonic (Mach 1.1-2.5)
Supersonic+ (Mach 2.5-5)
Hypersonic (Mach 5-10)
Hypersonic+ (Mach 10-25)
High Hypersonic (Mach 25-50)
High Hypersonic+ (Mach 50-100)
Massively Hypersonic (Mach 100-1000)
Massively Hypersonic+ (Mach 1000-8810.2)
Sub-Relativistic (1%-5% SoL)
Sub-Relativistic+ (5%-10% SoL)
Relativistic (10%-50% SoL)
Relativistic+ (50%-100% SoL)
Speed of Light
FTL (x1-10 Speed of Light)
FTL+ (x10-100 Speed of Light)
Massively FTL (x100-1000 Speed of Light)
Massively FTL+ (x1000+ Speed of Light)
Infinite Speed (Able to move while time literally stands still, or to travel anywhere instantly. Teleportation does not count.)
Immeasurable (Movement beyond linear time. This is why the speed cannot be measured. Given that S = D/T, if T is undefined the speed formula cannot be applied. This is the same reason why multiple temporal dimensions also grant immeasurable speed.)
Irrelevant (Characters beyond the concepts of dimensions themselves, including time. Meaning: Tier 1-A and above.)
Omnipresent (Higher-dimensional omnipresence of a certain plane of existence is superior to the immeasurable speed gained from existing on the same level. Similarly, immeasurable speed associated with a higher plane is superior to the omnipresence of a lower-dimensional entity. However, each case requires more detailed consideration.)
Note 1: The speed tiers used have intersecting limits, and this may be confusing to some members (especially new ones). The divisions are made based on Exclusive Form grouping, in which the true lower limit is the given lower limit and the true upper limit is just short of the given upper limit.
1) Mach 10 is Hypersonic+, not Hypersonic.
2) Mach 100 is Massively Hypersonic, not High Hypersonic+.
Note 2: Kindly note that MFTL+ (Often used shortly for Massively Faster Than Light+ or simply Massively FTL+) is a very broad category which starts anywhere from 1000x Speed of Light up to to any finite number. As such, MFTL+ characters need not be even remotely on a similar level of speed. In fact, the difference may be as great as the magnitude of difference between MFTL and regular human level. In conclusion, one MFTL+ character can speed blitz another MFTL+ character, and assuming otherwise without a logical reason is fallacious.
Note 3: Omnipresence must be specified in conjunction with the scale. Because omnipresence within a single 3+1-D universe (aka a regular 4-D space-time continuum) does not mean anything to regular life forms in higher dimensions of time and space (which might be larger and more complex than this universe).
Also, as Omnipresence is a variable speed level, a character that is omnipresent within a certain space is not necessarily swifter than all non-omnipresent beings. In addition, if a certain character is omnipresent on a universal scale (either 3-A or even Low 2-C), it is not a relevant advantage during a matchup against a character that can destroy universes (whether if it's the physical contents alone or even the whole universe and it's entire space-time continuum if the omnipresent being in question occupies either scale).
Note 4: Moving within a timeless void is not a sufficient justification for receiving the infinite speed rating. This is a rather common plot convenience within fiction, such as after a universe has been destroyed, or when traveling outside of regular space-time, and is generally strongly contradicted by all regular speed feats. In order to qualify, a character must be a natural part of that type of environment.
Note 5: Movement in a realm without space or time does not mean that a character has immeasurable speed within a realm of space and time, because there is no distance or time to be measured in the first place.
However, characters that are able to move backwards and forwards through time by movement alone technically qualify for immeasurable speed. But due to general inconsistencies, and the fact that several fictions grant this ability to any character able to move FTL, they should preferably be assigned an additional, independent, speed rating for the ability.
Another note worthy mention is that the difference between infinite and immeasurable: The former can go everywhere instantly, whereas the latter can go everywhere and everywhen.