width = "50" and "50%" are the same or not, and why ?

Answer 1

If you don't precise the percentage, it by default uses the pixel units
50px and 50% are completely different, the most important difference you should remind is that px looks fixed to the user whereas % keeps scaled as the user resize his browser

Answer 2

Not. 50% is half and 50 will probably default to pixels and 50px is not the same and 50% (unless it's 50% of 100px; then it would be correct).

Answer 3

*as