Will I be understood in Swedish speaking parts of Finland?
I understand to the best of my knowledge that Finnish-Swedish and Standard Swedish are quite intelligible to one another, but what sets them apart? Will the form of Swedish taught on Duolingo be well understood in parts of Swedish-Speaking Finland as well? What are some of the major differences between the two? Sorry if this question has been asked before! Tack så mycket!
The only major difference is pronunciation. Finnish-Swedish tends to use more Finnish phonology, which shouldn't come as a surprise. The difference is quite noticeable in speech, but it will probably not be an obstacle for communication.
As a native Standard Swedish speaker, I've never had any trouble understanding and speaking to a Finnish Swedish speaker and haven't noticed any difference in vocabulary what so ever, so you should be completely fine.
As a Swedish speaking Finn I can also assure you that we have no problems understanding standard Swedish spoken i Sweden. As mentioned the major difference is pronunciation. Especially the sounds sj, tj and r are pronounced differently - probably the way they were pronounced in Sweden in the middle ages when Swedes started to emigrate en masse to the coastal areas of Finland.