PU, tape and lace are not interchangeable terms. They each do a different job in a hair-loss system.

PU is the base material

PU means polyurethane. It creates a solid, smooth attachment surface in an area where I do not want an open mesh base.

Tape is the attachment

Hair-system tape is used where a bead has nothing to hold onto. If there is little or no support hair in a specific area, tape can give me another attachment option when the scalp and system design make it appropriate.

Lace gives me a finer, flatter base

Toupee lace can be used for closure and lace work where I need something finer and flatter than mesh. It is a different material from PU and it serves a different purpose.

I may combine them

A custom system does not have to use one material everywhere. One area may need open mesh, another may need lace, and another may need a solid PU section with tape because there is no dependable support hair there.

The decision depends on the scalp, the amount and location of natural hair, where the system needs security, and how visible that area will be.