Ummm, no. Those are two types of double edge safety razors only. There are single edge safety razors as well.
Double edge have the potential to be milder shavers in general. In general SE razors start somewhere in mid aggressiveness as compared to a DE razor. But there are rare and not terribly easy to find exceptions in the SE world.
The biggest difference I find in the shaves is that when a DE blade starts to get dull after just a few shaves it will announce that by drawing blood. It will grab the skin and since the blade is so thin it grabs, and springs back and cuts. A SE blade even when dull wont do that. It merely stops cutting efficiently and one changes it. Today I’ll have the 21st shave on my SE blade and getting to be close to the time to put in a new one. A long lived DE blade might give 8 shaves before a scheduled change. But a DE blade that gives 8 shaves isn’t the norm. Also, if a carbon steel SE blade is chosen it can be honed and used again. Can’t really do that with a DE blade though I heard of some appliances that claim they can sharpen them. They aren’t in general use within the traditional shaving community and if they worked they’d be in use by us.
SE also uses TTO, but there are other methods to hold a blade in place also, a flip top, and also slide it in place and flip a retainer tab up come to mind.
Where to get razors? There are modern made DE and SE razors being made today. But I far prefer the razors made in decades past.
It’s best to go onto the various shaving forums and buy from their buy/sell/trade sections. On ebay you can be sold pure junk, but on those sites you can be close to 100% certain of getting a usable razor. Too, you can learn about the aggressiveness of various razors. Some are as gentle as a caress, and others take lots of technique to use and walk away from the shave without blood. Starting out, esp’ from cartridges, you want a milder razor. Why? Because cartridges demand pressure against the skin to work. A safety razor demands just the opposite; no pressure to work best. I had a friend who I introduced to this shaving and after unsuccessfully trying for some time called me up to discuss it for the tenth time. I again told him to exert no pressure during the shave. He called me back soon after and said,“When you say no pressure you really mean no pressure don’t you!? I got the best shave of my life today!”. Yeah, no pressure means no pressure.
Anyway, there are shave forums where one can earn what needs to be learned. I strongly suggest making use of them if you want to be successful.
FWIW, price of a razor is no indicator of a better shave so don’t get drawn into that.