Is the Carrigan Forest walk the same as the Lough Navar scenic drive?

No.

Carrigan Forest’s Lough Formal route is a waymarked walking trail beginning from a Doagh Road parking area near Derrygonnelly. Lough Navar’s scenic drive and viewpoint system is a different forest visitor experience elsewhere in west Fermanagh. A car cannot be used in place of walking the Lough Formal trail. If your aim is a viewpoint reached by car, search for Lough Navar; if you want the Lough Formal walk, use the Carrigan Forest trailhead and black route waymarks.