are several key similarities between Star Wars and Star Trek power
generation technology. Trek technologies are more diverse, but Star
Wars fusion is more refined.
First, compact rechargable energy cells providing enormous amounts of energy - possibly gigajoules for something the size of a modern C or D cell - are available.
Second, compact, advanced, and highly reliable fusion generators are available in a broad variety of sizes. Star Trek's microfusion cells have been seen in smaller sizes than the smallest generator from TESB, but this does not necessarily indicate either side has more advanced fusion technology. Fusion technology is used extensively by both sides, and are found on nearly every sort of device and vehicle.
Critically, however, fusion generators are placed in the back seat for Star Trek starships. Although fusion generators are typically present as secondary systems, the primary generator of a Trek warship is an antimatter plant or artificial quantum singularity. Even in terms of space, a 100% efficient fusion generator burning metallic deuterium pellets requires seven times the cubage of fuel for the same effect as a slush antideuterium reactor, and a hundred times the mass of fuel. A singularity with a radius of R has a maximum energy of 6.07x1043R joules.
Of particular interest is the matchup between the power plants of Imperial and Federation ships. Although little can be said directly about the power outputs of the two, their energy reserves can be very well analyzed. Federation vessels use deuterium-fueled impulse engines (100-115 TJ/L, 630-740 TJ/kg) and deuterium/antideuterium fueled warp engines (14,800 TJ/L, 90,000 TJ/kg), while Imperial vessels use diesel-fueled fusion engines (70-230 TJ/L, 100-280 TJ/kg). For various reasons, the high end of this range is likely for Imperial vessels, while the low end is likely for impulse vessels.
It is not too unlikely, therefore, that an Imperial vessel will get over twice times as much energy per liter of fuel as an equivalent impulse-fueled Federation vessel; however, a warp powered vessel with the equivalent volume available for fuel and equipment will have 64-210 times the energy reserve. In both cases, the Federation vessel enjoys an advantage in fuel mass. There remains a certain tactical disadvantage for the Federation vessels in that antimatter will spontaneously explode far more violently than diesel fuel, given an opportunity; however, the strategic advantage of being able to field smaller ships of greater power and/or endurance is substantial.