A hardtop is a rigid form of automobile roof, typically metal, and integral to the vehicle's design, strength, and style.
1965 Rambler Marlin, a pillarless hardtop
1969 Australian Dodge Phoenix four-door sedan has a B-pillar and painted window frames
1969 Dodge DE Phoenix 400 pillarless hardtop coupe. The lack of a B-pillar and window frames, added vinyl roof, thickened C-pillar, and softened roofline creates an appearance similar to a convertible.
1976 Chrysler New Yorker with doors open. Note the absence of a driver's vent window and half-height pillar to which the rear doors attach.
A convertible or cabriolet is a passenger car that can be driven with or without a roof in place. The methods of retracting and storing the roof vary among eras and manufacturers.
2006–2007 Mazda MX-5/Miata roadster
1951 Hudson convertible
2001 BMW M3 convertible
1897 Daimler Grafton Phaeton