What are you putting over the top of of it? Either of those are just underlayment.

Need much more info. Underlayment for what kind of roofing?

That pitch is too low for shingles, water will wick and be a problem no matter what underlayment. That underlayment is not necessary for a continuous membrane roofing material or metal roofing. Have no experience with tile roofing materials, so no idea there.