To clean up means to make something not dirty- looking > I have to clean up before the guest arrive ( that is assuming you are dirty after repairing your car , for example) To tidy up means to make things look presentable or neat > I have to tidy up a bit before the guest arrive ( you are clean , but maybe your hair is in a mess ) Clean up the room >make the room completely "not dirty-looking" Tidy up the room > make the room completely neat or presentable looking .

Hello Leonardo! From my knowledge, both 'tidy' and 'clean' can both be used to describe cleanliness. Tidy is more of a description of being 'organized', while clean means to be free from dirt, marks, or stains. I hope I was able to help! -Farrah B. :)

I guess you clean up what is dirty (e.g. the kitchen after you've cooked a meal) and you tidy up what is not in order (e.g. the office after you've been working non-stop for a day or two). Hope that helps!

Apologies Leonardo, seeing Farrah B's answer, I realise that my response was much too informal. I totally agree with her answer also. Kieron

tidy up is smaller and implies personal/private ownership - you tidy your bedroom, but you would clean up someone else's house or a park or a town