Fit emphasizes the adaptation, assembly and tolerance fit of a few parts.

Clearance fit clearance fit and interference fit interference fit;

Installation refers to installation, such as a screw hole, and a small piece is sleeved into a large piece (the bracket is installed on the equipment: due to the different positions of the installation holes, we can't install this bracket on the machine);

Mount is used to indicate that many parts are more suitable to be put together. Fit these parts together.

Assemble is a more formal expression, which means to assemble into a finished product. If there is: Apple designed the iPhone in California and assembled it in China behind your phone.

Of course, I am not an English major. I hope you can correct me a lot, which is also good for me. Thank you.