Valve cover difference?

[thedude]

Hi there okay this may be a stupid question but here it is. What is the reason behind baffled valve covers and why they make non baffled ones too? Okay so it's really two questions in one

 

[EL5DEMON340]

keep oil from going into breather/pcv valve, the non baffled V/C's should be used with baffled breathers