Skills

Jump Phases

Jump is charged by holding space and the amount of charge determines how high they jump. This is not a straight launch into the air, the launch phase (straight after releasing space) has a natural arc where height steadily increases, then declines before they land. Contact with the ground (landing) automatically ends the jump animation.

Jump Height

Maximum jump height refers to the highest point of the jump arc. This means the rider must correctly judge their approach, charge and release (space) to gain the height necessary to make it over an obstacle. As jump skill increases, it becomes easier to clear lower level jumps with less preparation, but easier to "over jump". Outside of multiplayer server events that score players based on appropriate skill (using a jump height that matches the jump itself), this has no real significance to horse or rider.

Jump Distance

Jumping without pressing W plays a jump animation on the spot. It is holding W that gives the jump forward motion, and this is further affected by speed. Jumping in a higher gait (speed) covers more distance the faster you go, and this scales further depending on the gait used and the speed skill. Certain gaits - specifically walk, trot and canter - are fixed speeds and are unaffected by skill level, so a horse with level 1 and another with level 5 will not cover more distance while jumping at canter. At maximum speed and jump, it is possible to jump over gaps up to 11 blocks wide with good timing.

Jump Spacing

Jump spacing is important in planned courses - riders need enough time to approach the jump, charge, release and reach the appropriate height to clear an obstacle. The distance required between jumps depends on how tall they are and what speed the rider is expected to use. Read more here (Discord).

Jump Refusals

Jump refusals are very common in low level horses, but are not influenced by the jump skill or successful vs unsuccessful jumps.
Only affinity impacts refusal, so it is easier to begin training jump after increased bonding and training in other skills. 

Jump Collisions

There is no system in lite to identify jump collision ("faults") and obstacles are not knocked over if contact occurs.

 FUN FACT  

The most challenging jump is a 5B tall and 5B wide ascending triple bar.

It is only possible at a gallop and requires perfect timing to clear all bars and cover the entire jump distance without collision.

Universal Speeds

Walk, trot and canter use "universal" speeds, which means they are unaffected by speed skill. This was added for the convenience of multiplayer worlds to allow players to ride at a uniform speed in trail riding together or group routines, and engage in competitions where variable speed skill need not be factored in for time-based trials.

Experience

Experience gain from riding is calculated based on blocks covered (distance). Riding at a higher gait increases skill gain simply because it covers more ground and therefore gains more experience.

Skill Loss

Affinity is the only skill that can be decreased without commands. Points are decreased if the horse takes damage.

• The exact point calculation is unknown, as the deduction seems to vary by source:
• Hit from a player with an empty hand deducts 5 points ( 0.5  )
• Hit from a fully-charged unenchanted bow deducts 30 points ( 4  )
• Damage from cactus deducts 20+ points ( 0.5  )

Levels themselves can decrease if the skill points decrease beyond 0. For example, Affinity III becomes Affinity II. If the horse already has the lowest affinity, points remain at 0. The horse will automatically level up again once their points reach the experience threshold for the next level.

Other

• Affinity is not a bond to any specific rider, just an indication of it's receptiveness and gentling to riding commands. 
• Affinity is not varied by horses - all horses start at 0, all horses can be maxed, all horses gain affinity at the same rate.

Special

 TBC  Horses can be fed three items for a special points boost.

• Golden carrots - Up to 10 carrots can be fed for a boost of 100XP
• Golden Apple - Up to 10 apple can be fed for a boost of 200XP 
• Enchanted Golden Apple - 1 apple can be fed for a boost of 5000XP

These points only affect affinity and the limit applies for the horse's entire life. Once the cap is reached, attempting to use another item of that type will simply mount the horse instead. Feeding all three items to their maximum limits boosts a horse to Affinity IV (4), assuming the world uses default experience values.

 NOTE  Using an enchanted golden apple may not automatically convert points to levels, but riding will trigger the level up.

Survival Leveling

This could be an oversight of the lite system, or an intentionally defunct skill that was left for command or creative uses only. In the full mod, health skill is tied into the food system and points are earned from feeding. In lite, horses do not eat and food items are not included in the mod, therefore there is no (currently known) way to earn skill points in survival gameplay except for finding health potions in loot containers. 

This is not a complete list of changes or features. It is a log of wiki-related version information and may be outdated.