The consumable digging implements could vary in the following attributes:
The size is evident, every pick I've found has a 3x3 size. But I'm not immediately certain how the picks vary in power & durability.
The official wiki, Starbounder, currently answers this question on the Tools page.
For convenience, the relevant text is quoted below (2017-10-05, current Starbound version 1.3.2)
Pickaxes mine blocks in a 3x3 square 10 times per 3 seconds and break after 200 swings, which is about 1 minute of continuous use.
Drills mine blocks in a 2x2 square 10 times per second and break after 1000 ticks of damage, which is about 1 minute and 40 seconds of continuous use.
Damage dealt per hit depends only on the material composition of the tool. Copper, silver, gold, platinum and diamond tools deal, respectively, 1.5, 2.0, 2.5, 3.0 and 3.5 damage per hit.
