They’re two sides of the same coin.
UKIP are their closest political match.
Both single issue parties with no idea on the finer if any details of what they promote. UKIP however are far more odious with the racists they attract due to the anti-immigration propaganda.
The difference being that our Scottish brethren have shown over two referendums that they (the majority) won't vote for the unknown, regardless of how many unicorns you try to sell to them.
I'd hope (but not expect) that they would have learnt from this and when/if another Indy Ref happens then they have negotiated in advance with Westminster and the EU so voters know exactly what leaving the union means and not just another arbitrary question.