Kind of distinct but could solve similar problems where they overlap.

Worktrees let you have different branches from the same repo checked out to the file system at the same time, without needing seperate repos.

The clone --shared --reference-if-able and -dissociate options let you have multiple repos with less of a space hit.

They almost certainly can be used at the same time, though I've never heard of anyone doing so.

The limit of only having at most a single copy of each branch checked out, which makes sense for development purposes, made worktrees unsuitable for my use, which was mostly (ab)using git as a deployment tool.