"He doesn't wear other shirts."
Translation:הוא לא לובש חולצות אחרות.
What's the difference between "לא" and "אינו"? Would you use one over the other here?
You will read אינו/אינה on signs or on system messages on your computer, but hardly say it. For example אתר זה אינו קיים for : this website doesn't exist
There is not to him wears doesn't make sense so why is אינו allowed here!
Because that's not how you translate אינו. It's just like לא but more formal.
It is, but in that case the meaning is different. אינו/אינה/... is used sometimes in formal context instead of לא, I was confused about that in the past as well.