A simple Google search will answer that question. The simple answer is regular oil is refined from crude oil that comes from the ground while synthetic oil is made from another hydrocarbon, like natural gas, to make the oil. Semi-synthetic is a blend of the 2.
There is a more complicated answer that came from lawsuit between Castol and Mobil Oil but I won’t go into that here.
Yes, you can use synthetic oil in your CR-V. You can always use synthetic even if your car doesn’t require it (and I’d recommend it!) Some cars actually require synthetic oil OR specify oil grades that can ONLY be satisfied by synthetic oil. Like 0w20 or 0w40.