Now that you know the difference, think about it's potential use for you.
If you have a LARGE lawn, or plan to mow others lawns and golf courses then a finish mower. But these have light blades and hitting a rock can damage the blade, or as I was told a gopher mound. I have one but have yet to use it.
If you have big fields, brush, blackberries and saplings to cut down and land to reclaim, then go with the Brush "Hog" I have mowed scotchbroom over 10 feet tall with mine, and hit stumps and 5 lb rocks with no damage. Lots of noise, but no damage.