If you book regular fares, you'll find SBB and DB fares are virtually identical for the same trips. There is an international agreement between the European rail companies called CIV which basically tells them how to charge.
What the OP observed was special fares, often connected with restrictions (such as you have to take a certain train rather than having a choice of any train going in roughly the right direction on the right day, which you would have with a CIV ticket). The problem with the SBB booking system is that these special offers (often) don't show up.
Further advantages of the DB booking system versus the SBB one are:
- DB is better at finding obscure little places that SBB doesn't know anything about, not just in Germany but also in some other countries.
- most ticket can be bought and printed out immediately. If you're trying to do something very eclectic you may get a message that you should contact DB in person, but that happens rarely. The SBB system is more quickly driven to its limits.
Disadvanatages of DB vs SBB
- It's difficult to get things like GA acknowledged
Some other systems.
- SNCF is okay for booking within France but pretty useless on timetables. I sometimes find it useful to check train times on DB and then use SNCF to book (you get better offers on French trains sometimes):
- RENFE (Spain), DB and SBB do nomiinally cover Spain but they are really useless and miss out lots of stations and trains. the RENFE site is a bit cumbersome to use (that is, there are certain tricks you need to know to make it work better and reveal trains it will at first pretend don't exist) but you often get better deals for travel within Spain than on other sites. For anything outside Spain it's useless. Oh, and it says you have to be resident in Spain to use it. However, when I type my billing as Zürich, Spain, it accepts that. It obviously doesn't notice the credit card isn't a Spanish one.
- UK, for tickets in the UK, you should definitely go through one of the UK sites as DB will make you pay through the nose. Travel inside the UK is not part of CIV (only international tickets to or from the UK are) But havings aid that, I did once get a ridiculously low fare from DB for a UK train. I still believe it must have been a computer glitch as it was a peak time ticket (most UK special offers are off peak only) and it cost me about 10% of what the UK webistes were quoting me for the same journey. When I printed it out it had some very cryptic stuff printed on it and the ticket inspectors all took a long time looking at it but finally let it through.