A lowrer mash temp will create a more fermentable wort. A higher mash temp will create a less fermentable wort. It all has to do with enzymatic activity, and the types of sugars produced from starch conversion.
A lower mash temp normally produces a thinner, lighter bodied, drier tasting beer.
A higher mash temp would then lead to a thicker, heavier bodied, sweeter (perhaps maltier--depending on word choice) tasting beer.
Hope this helps.