As Ploshkin said, some have layers, some don't. (ITS do.)
It's also dependant on your printer. Some companies will toggle the layers for you, others will only print the whole thing as is. Be mindful too, of the cost of printing in colour as opposed to B&W. It's usually much cheaper to get B&W plan prints. Some printers not familiar with sewing patterns will see A0 and colour and assume its a colour poster print. The difference in price for me is $4.30/$32.00 per page!!
I really like Itch to Stitch patterns, they're well drafted and have good instructions.