Startup is just a code word for "tech company" anymore.
Kids: do not use either if you care about the judgment of your elders.
Bonus protip: until you vest, you should care.
It might be pragmatic to care about the judgment of one's ignorant elders, when the ignorant have power over you, but in no other sense should one care about such opinions.
Or if you're a VC, it's "tech company whose current valuation is based on future value"