The 7092 has two modes: Wave and Pulse. The 7096 has four: Wave, Pulse, Interval and Sequential. Both have food timers; the 7096 comes with a (naturally cycled) moonlight and one can be added separately to the 7092. The 7096 is programmed with computer software so has many more options for fine tuning, such as changing how long the food timer suspends the pumps.
Speaking very generally, pulse control is probably the best function for any aquarium and most useful on any controller. By colliding faster and slower moving columns of water, it most closely recreates currents found on reefs in the ocean and is probably the best overall for randomizing flow and creating natural turbulence. There isn't a coral alive that wouldn't be perfectly content with a properly configured pulsing powerhead.
Interval mode on the 7096 can be used to create longer period tidal and gyre currents. With two pumps on opposite ends of the tank, or just pointed away from each other, you can have one create pulsing flow in one direction for a period of minutes or hours, before switching to the other pump. When the pumps switch at the set interval, the dominant current direction in the tank switches, like an incoming or outgoing tide.
Sequential mode is really only used if you have three or more controllable pumps. By triggering the pumps in a closely timed sequence (first pump 1 is on, then pump 2 is added to pump 1, then pump 3 is added to 1 and 2, etc.) it creates large, powerful surges. The effect is very impressive, but it's really best used in much larger aquariums.
To make it simpler, the 7092 would be fine for your 75 and the pumps you have now. But go for the 7096 if you like having finer control, playing around with more options or want to plan ahead for possible upgrades.
