WRX - standard base model WRX for normal market
WRX Type RA - "Race Altered" WRX stripped of many luxuries as base model for building rally car
WRX STI - WRX modded by Subaru Technica International for better performance
WRX STI Type RA - "Race Altered" WRX STI stripped of many luxuries as STI base model for building rally car
Usually (not always) the Type RA lacks radio, aircond, power windows, soundproofing, body kits, etc...all the things not necessary for a race car - and also lighter
most RAs that make it to Malaysia would have already have these luxury items added back to make it more sellable...
STI models usually have higher power and torque, higher final drive and shorter gear ratios, maybe some extra performance bits from STI. for road car, go for STI models if you can stretch your budget a bit...
some RAs may come with strengthened gearbox...
but all this info is not for sure, because subaru always has many variations in models and specs...
check this out...
http://www.type-ra.co.uk/