Quinoline vs Isoquinoline - What's the difference?

As nouns the difference between quinoline and isoquinoline

 is that quinoline is (organic compound) any of a class of aromatic heterocyclic compounds containing a benzene ring fused with a pyridine ring; especially the simplest such compound, c9h7n while isoquinoline is (organic compound) an isomer of quinoline many of whose derivatives occur as alkaloids and are synthesized for use as dyes, pharmaceuticals etc.