bloozoo2 - Read the profile on the L200 at Planet Catfish, that'll explain things. They're very similar, only difference I know of is different catching locations and different colouring.
Accoring to the same profile, they grow to 18 cm (7.2 in).
Gorgeous! Love my big guy, hes getting really nice since i put him in the 6ft tank but i dont see him as much as i'd like! Gotta love my L200 too, hes the most active of all my plecs! love them both to bits.
We have a fully grown wild-caught L128 at work which is GORGEOUS, but its retailing at £95!!!! which equates to about £60-£65 to me, still too much to pay for 1 pleco though
bloozoo2: as well as the plante catfish explination theres a good article in may/june PFK called "green phantom plec i think" it's all about the answer to your question. in short they are the same species but as you go further up the river the markings change. i wont spoil the rest for you, worth a read (i'm sure like me you have a stack of back issues under your coffee table)