"However/Nevertheless (sin embargo/no obstante)" Do you think they are interchanged, that's for you! Just a bit of grammar. Lots of people think they are the same or don't know when they should use them. It is quite easy when someone shows it to you. If you are talking about something "good" or a good idea and you must join that with another one "bad" you have to say "however". Let's see an example: "We won the first prize, however we won't get the money until next month", you can see, the good phrase first: "Cool! we have won, wonderful" but then the bad one "Sh... we have to wait for the money". Unlike you get "nevertheless" to connect a bad situation or thought with another better, example: "It was raining all day, nevertheless we managed to go out". I do hope it were helpful to you. Bye