This is using VS Battles Wiki's scale, except modified
Speed is simply how fast a character can move in a given amount of time. There are four types of speed used for VS purposes: Attack Speed, Combat Speed, Reaction Speed and Travel Speed. The term "Speed" is normally referred 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.
The speed at which a character can react. This usually only grants a short movement upon reaction, several movements at the same speed switch it to combat speed. Say character A shoots at character B with a gun and character B dodges. That's their reaction speed. Keep in mind, sometimes a person aim dodges and it's not as good of a feat. For example let's say character A uses a minigun on character B, but the minigun takes a second or two to charge up and Character B see's this. If Character B dodges it's considered aim dodging since he/she knew the attack was going to happen. Reaction speed is reacting to an attack 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.
Travel Speed/Flight Speed
The speed at which a character or object flies a certain distance, like going from the earth to the sun for example.
High travel speed logically requires similar reaction speed in order to maneuver.
However, the problem with this supposition is that perceiving time at a proportionate rate to (for example) MFTL+ travel would also make it logically impossible to not go insane from any trip though the universe, as it would constantly feel like it took at least billions of years.
Building on this, it is much harder to write reasonable and entertaining stories and challenges for characters that perceive and can react to their surroundings at speeds that enormously transcend the speed of light. Any challenges and confrontations would logically be over in less than an instant.
Thus most fiction writers and franchises tend to gloss over these facts for the sake of suspension of disbelief, and make a great distinction between regular movement speed and flight speed.
Basically, most fictional characters do not remotely tend to exhibit FTL or higher movement or perception speed in regular encounters simply because they can fly that swiftly.
As such, a character should preferably prove that its regular movement speed is equal to or higher than its flight speed to be listed as such.
You can use this calculator to convert from one speed unit to another.
Subsonic (Faster than Eye) (Mach 0.1-0.5) (34.3-171.5 m/s or 76.7-383.6 mph)
Sub-Sonic+ (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)
MFTL: (x100-1000 Speed of Light
MFTL+: (x1000-1,000,000 Speed of Light)
High MFTL: (x1,000,000-1,000,000,000 Speed of Light)
High MFTL+: (x1,000,000,000 Speed of Light+)
Infinite Speed (As fast as desired)
Immeasurable (Higher-infinite set entities beyond linear time and aleph-naut infinite distance, and its' concepts of speed.)
Note 1: The speed tiers used have intersecting limits, and this may be confusing to some members. 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. Examples: Mach 10 is Hypersonic+, not Hypersonic. Mach 100 is Massively Hypersonic, not High Hypersonic+.
Note 2: For ships or vehicles in general, it is good to put the broad rating and their exact speed also. For spaceships that use FTL travel, it is preferred to use Lightyears per Day.