Several decades ago, I was told that the pecking order of tobacco was as follows:
1) Cigars get the best. They are rolled from whole leaves and those leaves are selected only from the very finest. The rest go to brokers.
2) Pipes are second on the list. Pipe tobacco is made up of high-quality leaf that is flawed to the point of being unsuitable for cigars.
3) Un-cut chewing tobacco is often made up of the leaves the pipe tobacco buyers don't buy off the brokers.
4) Dip and snuff are made up of the rejects from all the above.
5) Cigarettes. Commercial cigarettes aren't really made of tobacco, per say, but rather from clippings and grinds. They are then rinsed and a tobacco wort, or soup, is made. This wort is then sprayed onto plant emulsion (like paper) and then flavored and sliced up to resemble tobacco.
Yes, many pipe tobaccos are flavored using various methods, including infusion. More extensive fermentation is also employed in producing many fine pipe blends; far more than you'd see in a premium cigar.