Yup, essentially a deep cycle RV/marine battery can handle multiple discharges, whereas a car battery is designed to rarely ever discharge much below 12 volts and doing so to one of those will cause it to fail quicker.
Yes, you could probably use a car battery on a temporary basis, but it probably wouldn't supply you with power for very long compared to a deep cycle.
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9467.8 (as of 5/26/19)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR