Cels Forum

Try looking at Brian's Animation Info page, conveniently 
linked from Cels.org. ^_^ He gives an incredibly detailed 
explanation.
One thing I've noticed is that in genga, the sequence numbers 
can be anywhere on the page and are always circled, whereas 
with douga they are always in the strip with the pegholes, 
upper right (or lower right with bottom pegs).
Mata ne
Ryochan