Starter VS Sourdough Starter?

Starter VS Sourdough Starter?

The title of this forum seems to answer my question but it is not what I am finding in the other world.

95% of all internet hits all mention sourdough starters.  When I use -sourdough, all I get is an Amish recipe for a starter and it is repeated in dozens of sites.

Is there a difference between a starter and a sourdough starter?
If so, what?

Source: Fresh Loaf