No, it's a little more complicated than that. For any given cartridge and barrel length, there will be a range of powders that will work effectively, then there will be some that are too fast or too slow to work well, usually.
Big bottlenecked cartridges and long barrels will tend to slower powders, straight necks and shorter barrels to lighter powders.
Heavier loads in a given cartridge are usually a little slower, relatively faster powders are usually better for lighter loads... but this is a generalization and should not be relied on for experimentation. The powder and bullet companies have paid people to experiment for us and publish the results, so use that information.
Slower powders, all else equal, will have more flash, more powder burning outside the barrel.
Slower powders will reach peak pressure later than faster powders, but that may or may not result in the same, or more, or less velocity depending on all the other factors involved.
If you are interested in researching this as a sort of semi-scientific investigation, get a big reloading manual and look at the data for the different powders in different calendars... chart powders across calibers and calibers across powders......