There are differences, but as Gaenth pointed out there are ways to make their performances similar. A true delta wing needs a forward-edge sweep of at least a certain degree (my memory fails me--anyone got it offhand?) so no American planes qualify, although the F-15 came close to being a clipped delta. Deltas give low drag at high speed and mid to high altitude, but they give a rough ride at low level and are not efficient at low speeds. In order to counter this, forward canards give a little bit of extra lift at the front but more importantly create vortices that energize the boundary layer over the wing at low speed and high AoA. Like anything else, wing shape is a function of role, in that different shapes have different aerodynamic qualities at different speeds, altitudes, and AoA. The A-10, for example, has long straight wings because those are most efficient at low speed (<Mach1) and low altitudes, where A-10s spend all their time. Swing-wing fighters provided a pre-fly-by-wire solution to the efficiency problem by enabling the wing "shape" to change depending on flight profile. Once computers were able to start making small changes in wing shape (via ailerons and flaps) several times per second to account for all kinds of changing air characteristics, such mechanically complicated and heavy means were no longer necessary. If your main flight profile is going to be at medium altitude, there's not much reason not to have a configuration like Gripen/Typhoon/Rafale. F-22 and F-35 wingplans are heavily influenced by the need for low radar observability (not to say stealth), but thanks to FBW they don't have to look like F-117.
Sorry for the long-winded reply. There's lots of good aerodynamics info out there, and I'm sure some of the regulars here have a better understanding of it than I.
