AfaIk, posts and comments cannot be exported.
For the rest you may use the “export settings” function in the “personal settings” section on the webpage of your Lemmy instance (yet I don’t know what is actually exported).
Alternatively, you may use one of the tools mentioned in this post (the post is in German, the linked webpages are in English): https://slrpnk.net/post/10923543
The main difference, as I understand, is that national socialism is inherently racist and puts the (Aryan) race on top of the ideology, everything else must submit to the benefit of the (Aryan) race, whereas fascism puts the benefit of the state on top.
https://historyplex.com/difference-between-fascism-nazism
Trump, as far as I can judge from beyond the pond, is still claiming to put the state, or the United States of America, first, like a fascist would do. His hate speech against immigrants still serves the narrative of them being bad for the US, not of them being disadvantageous towards the benefit of the Aryan race.