If you're heading into the backcountry, dedicated touring skis make a real difference. The biggest factor is weight—when you're climbing uphill for hours, every extra ounce on your feet compounds quickly. Backcountry skis are built lighter than resort skis, which means less fatigue on the ascent and easier maneuverability in variable off-piste snow.
You can technically tour on resort skis, and some skiers do for short sidecountry laps. Just know that heavier skis will slow you down on the up and make kick turns more work. Also, make sure your skis have the right binding mounts—backcountry bindings like tech/pin bindings require specific drill patterns that not all skis support.
The trade-off is that lighter touring skis won't charge as hard at resort speeds on firm snow. If you're splitting time 50/50 between resort and backcountry, look for a touring-minded all-mountain ski that balances weight savings with enough substance for confident downhill performance.