How do you differentiate between recovery from telogen effluvium and male pattern baldness?

I suggest seeing a hair loss expert now to go over your condition and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone and/or hair transplantation. See an expert. Best, Dr. Emer

Great question.   Understanding the answer to this question really takes into account a full review of many of the hair cycle changes during telogen effluvium as well as androgenetic alopecia. In short there's three ways that you can answer your question. First, time is the greatest and most definitive way. If this is a resolving telogen effluvium, there should be a significant improvement in hair density over 6 to 9 months. For most with resolving TE, the hair density should be completely back to normal at that time.  Second if this is actually androgenetic alopecia a worsening of hair density will likely occur over a 12 month period. At best, the hair density would probably be the same but it would be very unlikely for it to improve unless there was some components of seborrhoeic dermatitis that was adequately treated that led to a minor improvement of the overall appearance of the  androgenetic alopecia.  Third, the other way to determine if this is a result of telogen effluvium or androgenetic alopecia is to perform self diagnosis. This is of course the most dangerous of all the options but nevertheless it's a common way. True androgenetic alopecia has less density on the top middle and front of the scalp compared to the back of the scalp. In other words truemale balding is a patterned hair loss. In telogen effluvium, the density is reduced equally all over the scalp.  I would encourage you to see your dermatologist to review whether a resolving TE or genetic hair loss is in fact what you have.  I would like to point out that the vast majority of males who are wondering about telogen effluvium or androgenetic alopecia generally turn out to have androgenetic alopecia.  Exceptions exist. The early stages of androgenetic alopecia are associated with shedding which give a confusing clinical picture.  The same is true with women as well  although true effluviums are much more common in women than in men. Overall. I would encourage you to see a physician to review the accurate diagnosis. 

Miniaturization and the patient's history is the short answer.  BOth are helped by minoxidil, finasteride, and LLLT (and some select shampoos), but they can also co-exist which means you need an experienced hair doctor to help you tease out the main actor at any particular time.  Haircheck devices and taking weekly hair counts can also inform the diagnosis.
Good luck!