The main feature separating it from the Latin alphabet are the three additional vowels, "Å", "Ä" and "Ö".
The characters "Å", "Ä" and "Ö" looking similar to German umlauts ('ü', 'ä', 'ö') are in fact considered letters of their own merits, despite them representing sounds similar to the corresponding sounds in German. As it's not a case of marking grammatical variation, i.e. of tempus or modus, or of syllable modification (diaeresis), it is in fact not a case of diacritical marking, and it ought to be improper to call these characters umlauts. However, no better name is known in English.
The other feature is omission of the letter "W", which is seen as a variant of "V", even though it is still recognised and maintained in names. Also "Ü" is recognised, but only used in names of German origin.
Apart from this, diacritic marks are also used for "à" and "é". These are seen as variants of "a" and "e" and the accents are usually omitted for capital letters.
See also: Letter Å, Letter Ä, Letter Ö, Finnish alphabet, Danish alphabet, Norwegian alphabet, Futhark