Treatment or the way someone/something is handled — refers to service, treatment, or how one deals with a person or item.
この病院は患者の扱いがとても丁寧だ。
This hospital treats patients very politely.
彼は若手ながらも一流選手として扱われている。
Although young, he is treated as a top-class player.
特別扱いは競争を阻害することがある。
Special treatment can sometimes inhibit competition.
The handling or operation of machines, tools, or products — refers to usage, operation, or management.
この機械の扱いは簡単なので、初心者でも使える。
This machine is easy to operate, so even beginners can use it.
薬の扱いには十分注意してください。
Please be very careful when handling the medicine.
丁寧な扱いが製品の寿命を延ばす。
Careful handling prolongs the life of a product.
Used as a suffix meaning 'to treat as' or 'to regard as' — e.g. X扱い means 'to treat X as ...'.
彼を子供扱いしないでください。
Please don't treat him like a child.
社員扱いされなかったので不満が出た。
There was dissatisfaction because he wasn't treated as a full employee.
問題行動を一度のミスとして扱うべきではない。
You shouldn't treat problematic behavior as a one-time mistake.