part 1 drawing^

part 2 drawing ^

part 3 drawing^

1. Size dimensions describe the size of each geometric feature whereas location dimensions describe the location of each geometric feature within a view.
2. Datum dimensioning is where a single reference point for a single direction is used for all dimensions.Chain dimensioning is where each point is measured to the next point. Datum dimensioning usually results in smaller dimensional deviation. 
3. Through a dimensioned drawing you can physically see the object and see the dimensions in relation to the others. In a written description you can only visualize the object and get the general idea of it based on the description. Both written descriptions and dimensioned drawings are used to give information about the objects.