Logs are a block that can be collected by hand but the tool to use is an axe for maximum log chopping power!
Dirt is easier to break than practically any block. However you should use the shovel to make it easier.
A hard sturdy building material however it is not explosion proof, a pick is the only thing that can collect it, along with TNT!
Sand is affected by gravity, and will be destroyed by hand however it would be advised to use a shovel.
Gravel is affected by gravity just like sand, and can be collected by hand however a shovel would be advised. When it breaks it ether drops a gravel block or a piece of flint. Remember the deeper in the ground you are the more likely it will give you flint.