I've got used to shovels that have a pointed blade like this:
which is more or less the right shape for digging ground. Now the very same shovel (same handle, same everything) comes in this design with a rounded blade:
which I'd guess would not stick into soil as well as the pointed one. Still there're plenty of such shovel offerings.
When would I use the latter design (rounded blade) shovel instead of the former design (pointed blade) shovel?
First, let me just say that these look like spades, not shovels, although I think in America the terms seem to be interchangeable, so it's moot. A shovel is broader, with a dished shape, usually with a raised ridge along either edge left and right, running vertically. A spade is more or less flat from side to side, and often has a ridge at the top, horizontally placed, for putting your foot onto when digging.
Pointed spades like the one in your first picture are designed to make digging lighter work - it's easier to penetrate the ground with the point, and the spade itself holds less soil, making it lighter to use. These are intended for people with less body strength.
I did a little looking around on landscapers sites to see what I could find. One thing I noticed is that transplanting spades have the rounded tip as compared to digging spades which have the pointed tip. Transplanting spades also have a longer spoon which your example does not. This leads me to guess that the shovel with the rounded tip is for situations where you would want to preserve the ball of soil unharmed, such as digging up small plants to move, whereas the pointed shovel would be used when you want to take as big a bite as possible without concern about the ball of soil staying in one piece, such as turning soil or digging a ditch.
