The large power plants based on oil, coal, natural gas, nuclear, etc. are thermal power stations. They use heat to convert liquid water into steam, which then drives steam turbines. These necessarily (by the laws of thermodynamics) produce a lot of waste heat. More than half of the energy used to heat the water is not turned into power at the end.
The waste heat is dumped in the large condensers of the cooling towers, which often have the characteristic hyperboloid shape because it's the most efficient form. This requires a lot of space.
So a commercial fusion system for large-scale use, if it can be built, would likely be little different than a nuclear power plant now, because it requires a big steam turbine at a large facility.
On a smaller scale, you might replace a large ship's diesel engines with electrically-driven fusion powered systems. This would reduce ship pollution and reduce the number of times it needs to refuel. (Assuming that a perfected system needs little maintenance otherwise.)
We don't think it's possible to get fusion power to an even smaller scale, other than people whose proposals and work are difficult to distinguish from a perpetual motion machine scams.
If we did have Mr. Fusion, then it would be a game changer. We would be able to have airplanes and helicopters driven by electric motors, powered by Mr. Fusion. You could probably think about the other things possible of power were essentially free. What about heaters under the sidewalks to melt the ice? I loved going to the outdoor heated pools in Iceland, heated by cheap geothermal. With free power, we would see more outdoor pools elsewhere. More people would have hothouses for growing flowers and plants in winter. Canada could become a major producer of orchids. People in Haiti wouldn't have to strip their country of trees in order to get power. And so on.
Mr. Fusion isn't going to happen, at least not soon. We'll still need transmission lines. This sets a lower limit on the cost of power. Life would be like in Iceland or the Pacific NW, where power is cheap enough that aluminum smelters relocated there for access to cheap power, or where data centers get located in the Dells for cheap power and cooling for data centers. (And where farmers use the cheap power for moving water around.)
In other words, not much different than it is now. Except with less dependency on petroleum sources and the global politics that that entails.