Whiteboard ledges?

I went to Lowes today to get some pine to make ledges for my boys and when asking the guy helping me he said that whiteboard was the same as the pine they had across the isle but was cheaper. He said the one labeled as pine was more expensive because it didn't have knots and such in it and directed me to the whiteboard one and told me it was kiln dried. So I trusted him and got that one and went home and hubby made a few ledges and we put them in their cage. I have read conflicting things some say whiteboard is ok but some say it has to be just the kind labeled pine so I'm not sure if I should take the ledges out and go get the other board or if these ones are fine?