I saw stoves with flat glass-like surface and there red glowing circles inside when they're on. Are those a gas stoves? Are there gas stoves with fire inside or those flat stoves are all electric?
Gas stoves will always have "open" heating elements because the gas requires oxygen in order to burn and generate heat. Anytime you see a closed, glassed-over heating element, the heat is electric in source. However without more information about the design of the stove, it can't really be determined whether the heat is a traditional radiant heat element or an induction element (in which case the red glow may be cosmetic, generated only by lights to indicate that the burner is on).