Fairly certain they are the same thing.
Yes they are. Thallium is the usual isotope used in a nuclear stress test. There are many
names for this same thing. Nuclear perfusion test, nuclear stress test, thallium stress test, thallium scan etc etc. Maybe they should standardise on the name to make it less
Actually, a Thallium stress test is a type of nuclear stress test. It's called that because it uses Thallium as a tracer. There are others as well, but this is the most common.