It is never a silly question if you do not know the answer!! dunster has already answered it - but I will add that for the most part sergers are used for construction and are especially helpful on cotton knits and items that fray. Embroidery machines are use for embellishment for the most part (though now there are designers that are creating patterns now that will embroider and quilt one block at a time. Prices do vary within each type from reasonable to pricey - the higher cost ones providing more bells and whistles.