Okay, to start off, the basic difference between prokaryotic cells and eukaryotic cells is prokaryotic cells are cells without a nucleus, and eukaryotic cells are cells that contain a nucleus.
So based off that information alone, you can answer #1. Cell A does not have a nucleus (big circle shape), while Cell B does. Therefore, Cell A is the prokaryotic cell.
As for #2, prokaryotic cells and eukaryotic cells DO have similarities despite their differences. For instance, they both have some of the same organelles, like the plasma membrane, ribosomes, cytoplasm, and DNA.
Finally for #3, two differences are that #1, prokaryotic cells have nucleoids while eukaryotic cells have a nucleus, and #2, prokaryotes have circular DNA while eukaryotes have linear DNA.
Your best bet is finding a visual aid in a textbook or online to help you, so you can better identify organelles and eukaryotic/prokaryotic cells. Also, there are some cheesy videos out there on YouTube which I was forced to sit through in Bio class last year such as the Amoeba Sister's youtube channel which could help. Hope this helped!
