Here's a website with a great explanation of the types of finishes.
Swedish finish was developed in the early 1950′s in Scandinavia and quickly gained popularity in Europe. It has been the industry standard here in the Northwest for about 20 years, probably because it is a truly ‘no wax’ finish. The only maintenance required is light damp mopping, as opposed to the semi-annual waxing and buffing associated with sealer/ wax and polyurethane finish systems. Swedish finish also has a reputation for durability unmatched by all but a few heavy-duty commercial grade finishes. Swedish finish is an alcohol-based acid-curing conversion varnish. It has been the industry standard for durability in the Northwest for many years, and we consistently achieve excellent results with Swedish finish. Because Swedish finish contains many solvents, it is highly volatile and toxic, and requires special precautions, including customers planning to be off the premises for at least a day or two after the final coat is applied, as well as removing pets and plants from the work area for the same duration. We may also ask that appliances with pilot lights be turned off or disconnected prior to the commencement of work. Please be prepared to re-light any pilot lights that we may have turned off. Light foot traffic may resume and furniture may be replaced after 24 to 48 hours, but the finish is not fully cured for up to 60 days, and therefore area rugs should not be put back on the floor for as long as is tolerable (if areas are covered before the end of this curing period, the covered areas will cure more slowly, and could result in more pronounced color differences between exposed and covered areas). Swedish finish is a two-coat procedure. The primary disadvantage of the Swedish finish is the powerful and unpleasant odor. We generally apply 2 coats of Swedish finish on successive days, and Seattle Floor Service always recommends vacating the premises while these coats of finish are being applied. Sensitivity to the solvents in the finish varies greatly from individual to individual, and some customers have reported a lingering odor for as long as a week after the final coat is applied. The majority of our customers who choose Swedish finish, however, find that if the house can be aired out soon after the final coat is dry, they are able to move back in the next day.