What is the difference between a semi-permeable membrane (parchment paper, cellophane paper, etc.) and a differentially permeable membrane (cell membrane)?

Semi permeable membrane will allow something to pass  through them and something not and it will allow on the basis of size particles
while differentialy permeable will include other factors also other than size and will depend on the need of the cell
this is the main difference between them
hope it helps

Droughts cause very arid places such as a desert

The answer is one amu.