Here's an example of 1960's ska (and one of my favorite songs):
Now all the bands in the 1980's/1990's that are categorized as ska are more properly referred to as New Age/Third Wave ska. This includes bands such as: Sublime, Reel Big Fish, Mighty Mighty Bosstones, Save Ferris etc.
Very similar, but with obvious differences. Third Wave ska introduced more influences of punk music that was made popular in the late 1970's and 1980's when punk music and hardcore punk became a sub cultural phenomenon in the US and England. Punk influences ska, reggae influences punk, but everything in popular music (and I mean literally everything) comes from blues music.
I could write a freakin' book on music especially punk, ska, and reggae.
Sorry I had to go off like that I just can't help myself when it comes to music.
Let's put the women and children to bed and go lookin' for dinner
Do you know the movie This is England? If you don't it's a great movie and has all of those punk/ska bands in there. It's about the skinhead movement in the 1980' in England, and of course Ska was very popular in that era like you mentioned.