There are people that vote for SD for all kinds of strange reasons, but 90% of those who do, have immigration and the EU as their reason. The same I'm certain is true for PS.
I doubt that this is true for PS. I have the impression that PS, as Helsinkian stated, is able to attract more voters on economic issues than SD. That's logical. It needs to do so in order to win many votes, because in Finland immigration has not been nearly as salient an issue as in Sweden (until recently). "Mass immigration" wasn't an actual thing in Finland until this year - of course it was part of PS' rhetoric, but the effects of third-world immigration used to be much less relevant to Finnish voters and to Finland than to Swedish voters and to Sweden because of the enormous difference in numbers.
The EU, on the other hand, seemed more salient in Finland than in Sweden: I think PS attracts more voters on the basis of their EU-related views than SD does. Again, this is logical, because Sweden isn't in the eurozone.