Best way is to learn hands on, most home depot’s offer free classes on basic electrical work like how to wire a light switch. May not apply specifically to smart switches, but you’ll learn how to use a multimeter, which is essential to knowing which wire is which.
There’s a good chance the’re neutrals. But you have to connect them both to the switch. GE smart switches accommodate 2 wires on each terminal. Check terminal labeling.
I would however verify voltage first. Invest in a little voltmeter, nothing fancy.
Same issue with me
Did NomadTech’s suggestion work?