Pharmer.org

Any difference between the (slightly) different oxy diagrams on rxlist.com? Perc shows ch3, into N, then a line to another spot on the diagram.

Roxicodone shows ch3 into N, changing to ch2, THEN a line to the other spot on the drawing...

OxyContin shows something similar to perc, but shows (-c1) between ch3 and N...

There is no difference between Perc, Roxi, or OxyContin, correct? These "differences"  in the diagram are nothing? Is that correct?

Also........why do other diagrams show (M) in place of (CH)? I hope these questions make sense as I would really like to understand more, yet know nothing about chemistry...

Thanks for any answers