In all reality the only difference is 50cc you do not need a motorcycle endorsement everything else above it you do that's why they make 50cc so you don't have to have a motorcycle endorsement that is the only difference besides the bigger the CC the faster the scooter and 50 CC's do not do 45 miles an hour stock but with my new intake and exhaust mine now does 52 miles per hour
50cc goes about 40 mps and can only take on highway speeds 45 mps or less with a helmet only if not I sured With helmet if insured you can do it. The 150 cc goes like a lot faster and can be driven on hwy with speeds over 55 mps And they are more costly, plus both require drivers license but no insurance hence the hwy factor W/o helmet worn. Hope that answers your question.
Thanks! Your answer is awaiting moderation.