difinitive traits:
tropical gar has a broader snout, young has trident pattern on head.
other traits:
most of the time, florida have a more spotted patterng whereas trops have blotches/stritations. trops usually have larger fins compared to florida gar.
note that all gars have 2 rows of teeth, so if you see 2 rows on the upper jaw it doesn't mean you have a gator or trop. it could also be a florida.