Battlecast, Full Metal, Mecha, Project, and Program
Just trying to high-light and compare all the distinct features of each skin lines mentioned in the title:
Battlecast - 
- Probably the 1st well established SF skin line in league
- Created by Victor
- Evil people-killing machines (refer to Terminator series)
- Black metallic body
- Red illuminations
- Heavy duty machinery style (dat black smoke coming out from the exhaust pipe)
- Can transform to some extent but very limited
- Were some intellectual(?) creatures before being captured and rebuilt by Victor
- Mind-manipulated to become a pilot A.I. that serves Victor
Full Metal
- Said to be the rival SF skin line to Battlecast
- Created by Jayce
- Champs wearing full body armor suit (refer to Ironman)
- Main color: Metallic Silver
- Minor color may vary (Jayce being blue)
Mecha
- Created by yordles
- Giant Kaiju-fighting robot (refer to Pacific Rim)
- Size wise, probably has the largest scale
- Theme colors may vary, but they all looks very cartoonish
- Heavy duty machinery style, but somewhat more futuristic
- Can perform partial or total transformation (refer to Transformers)
- Can deploy energy field
- Seems like they are meant to be operated by pilots, but somehow they can move by themselves(?)
Project
- Creator's identity is unknown
- Cybot nimble fighters (refer to Metal Gear Rising)
- Futuristic level rekt Full Metal lines (Jayce you suck)
- But seriously Full Metal Jayce is legit for Project: Jayce
- Main color: Metallic grey
- Each one has their own symbolic minor color (Power Rangers?)
- Everybody have a visor
- Probably the 1st skin line that has a group recall. (Yasuo what are you doing there, stop being the odd)
Program
- Creator's identity is unknown
- Futuristic humanoid robots
- Orianna 2.0?
