No, you are not using the standard definition of a thread [1]. What you are calling a thread would normally be called a userspace thread, green thread, fiber, stackful coroutine, etc. Note the specific qualifiers distinguishing them from the overarching concept of a thread which can be broadly classified as a scheduled instruction stream.

edit: Just to be clear, "thread" is itself also just one of many names for the general concept. Task, Activity, Actor, etc. may be used, but they might also refer to something completely different. It is really a question of checking that the properties of the named thing match the properties of the standard definition of a "thread".

[1] https://en.wikipedia.org/wiki/Thread_(computing)

you are right, I guess the main difference is whether the process or thread has its own memory or not, if it does it's a process, if it shares memory, it's a thread.