telogen effluvium is usually overall/large area diffuse thinning, alopecia areata is usually patches, male pattern usually happens in a norwood pattern. this graphic's for women but it illustrates it well, men can get te and aa too.
dermatologist can tell with a biopsy. if you already have a derma and they just looked at it go back and ask for a scalp biopsy or 2nd look tell them your situation. get an independent 2nd opinion if you don't get anywhere doing that.
te is usually stress induced and often eventually goes away on its own but not always. aa doesn't have a known cause yet.