Wow so many replies, I did not expect that thank you all so much, you are very helpful!
From what I've read (from those instruction booklets you get with the machine - I downloaded it from the website) both of them have the basic stitches, adjustable stitch length and width, buttonhole foot, zipper foot and blind hem attachments, adjustable pressure and extra lift of the foot, which feels like everything I would need to at least get started. They're both supposed to have the ability to do a double stitch, however I have no idea where a second spool of thread would go on the 3210 one, as there is only space for one as far as I know on the top portion of the machine. I saw this:
https://www.youtube.com/watch?v=vTrUeC73ih8 and it's so pretty and nice and amazing and I'm crazy so I guarantee you, I will do this one day
3210 seems like a beast, judging from this video:
https://www.youtube.com/watch?v=U-UeWCJ5M84 But I really dislike the way it looks... I wish I could find a video or something demonstrating sewing thicker fabrics or more layers of a fabric on the 240 one, because I really love everything about it. I don't think it should have a problem with a couple of layers of denim or? I'm not sure if I could test the machines, I guess I'll take some denim with me next time and ask, shouldn't hurt to ask. I just have to pretend to know what I'm doing.
They both have plastic outsides, but they seem quite heavy (240 is around 8 kg, 3210 is around 11 kg based on information from amazon) so my guess is they have to have a lot of metal inside. I could be wrong. I remember we had an all metal machine and it was so heavy I could barely lift it up a little from the floor, I couldn't even put it on the table (it was mostly stored and only used occasionally, I did sew a bit with it but that was years ago). But yeah I plan on getting it from the specialized store.
I did look at some other Elnas in the same price range and couldn't find anything available that would be purely mechanical. They all have some screens and displays and I just want buttons. I don't need a screen to tell me which stitch I'm using I can easily check that myself.
I know some computerized and electronic ones can be more powerful and work great, but I don't know, I just don't feel that comfortable with all touch screens and fancy stuff that could get broken some day and would take 10 professionals to fix it (okay I'm exaggerating lol, but you get the point).