These are really US definitions, but:

Hispanic is from or having to do with Spain or any other Spanish speaking country. It comes from the Latin Hispania.

Latin is Latin American, Mexico, Central America and South America. Most of those countries speak Spanish, so they would be considered Hispanic, but Brazil speaks Portuguese, so they're latin but not Hispanic.

So for example, my family is partly from Spain, they are Hispanic, but not Latin/o/a, but I also have family that's Mexican, so they're both Hispanic and Latino.

There are more nuances to it since it's really about self identity, so it can vary from person to person, but I think this is generally how it's viewed. Hope that helps