〜気味 と 〜がち と 疲れ気味 vs 疲れがち はどう違いますか？説明が難しい場合は、例文を教えて下さい。

~気味 means "a little bit~" and the state could be either temporary or continuous/frequent. Usually shorter term than ~ がち。
On the other hand ~がちmeans the state occur frequently or is lasting.

Ex) 最近疲れ気味なんだ: lately I have been a little tired.
今日は疲れ気味なんだ: today I am a little bit tired.

最近疲れがちなんだよね: Recently I feel tired pretty often.
彼は病気がちだ: He often gets sick.

Hope this helps!