Good dark roast is typically made of a robusta/Arabica blend and is usually split-batched to keep it even or dried slightly beforehand to help it get darker faster.
French roast, generally, is the “throw it in a pot and burn the shit out of it” variety. Other dark roasts aren’t typically like French roast.
Like, look at Peet’s Arabian Mocha Java. It’s a dark roast that’s smooth and slightly sweet. The smoky notes are subtle, and the cocoa helps balance everything. It’s been roasted long enough to draw out a deeper flavor, while still maintaining a mild body.
Generally speaking as well, if you notice “froth” or bubbles on top of your coffee, it’s a pretty good sign that your coffee is of high quality and the beans were properly taken care of during the preparation process.