Very small. möta sounds a bit more serious than träffa, and a möte (meeting) is definitely more serious than a träff (date, hookup, informal gathering)
I am using Rosetta Stone in addition to Duolingo, and on Rosetta Stone, they are teaching me to use "träffar". What is the difference between träffar and träffas?
träffas has reciprocal meaning, it means that it doesn't require an object because the subject of the verb is doing the action to 'itself' (= each other). träffar is a normal verb that doesn't make sense without an object. You can't just say Vi träffar in Swedish, you'd immediately be asked who you're meeting. So Vi träffas means the same as Vi träffar varandra.
So, if I am saying that we are meeting someone without indicating who, I would use träffas, but if I am saying who I am meeting, I would use träffar? (Jag träffar min mamma på restaurangen, for example)?
It's not possible to say you're meeting someone without indicating who, at least grammatically (you'd have to say e.g. 'någon', and then there would be an object). träffas means the people who are doing it are meeting each other. But if there is an object, you use träffar, so your sentence is ok.
Like: jag träffar min mamma or jag och min mamma träffas.
It's starting to make a little more sense, now. In your examples one is " I am meeting my mom.", and the other is "me and my mom are meeting."?
I know this is a very old post, but is "vi träffas" the best way to say that, or is "vi träffar varandra" used just as frequently?
Even later answer, I must have missed this comment. Vi träffas is most natural in most contexts. I mean, if I want to say 'we meet often', either could work, but if I wanted to say 'Let's meet at 8' I'd hardly use the version with varandra.
So, 'Vi traffar (I'm using a different device and cannot use the different letters)' is basically 'we meet' in the ambiguous context, whereas 'Vi traffas' is basically telling someone that you two are going to meet?
You just can't say vi träffar, you have to add an object for it to be an acceptable sentence.
What would be a similar sentence in English (not necessarily about meeting people, but a random sentence that wouldn't make sense without an object) so I can relate? Also I know that vi träffar wouldn't make sense, I was using it in the way you would say 'to meet'.
I can't think of anything reciprocal, but a sentence in the course where the English verb needs an object but the Swedish doesn't is Hon tackade för maten which translates into 'She said thanks for the food' – or you could add who she thanked, but in Swedish you don't need to mention them. So you can say Han tackade och gick literally 'He thanked and left' which of course doesn't work in English.