What is the difference between a self-propelled howitzer and a tank?
I just clicked on the link and I would say that there is a big difference. I would rather be in the tank. There is technical difference and each piece of equipment has its purpose, so I am sure there would be situations where I would rather be in the artillery piece, but I was just trying to be funny considering the picture on the link.
A howitzer is a relatively short cannon that delivers shells at a medium muzzle velocity,and fires a shell at very long trajectories. A tank, its is a tracked vehicle which combines a offensive ability and defensive abilities
An old adage is that the Artillery is the King of Battle as it places the "balls" (various ordinance) right where the Infantry (Queen of Battle) needs them!
Although artillery can be used in a direct fire capacity, it typically fires indirect in support of maneuver units in direct contact with enemy forces. The 155mm gun on a US M109 Howitzer has a range of (give or take) 20 km. Typically a battery (4 guns) will set up, and be able to place indirect fire on targets with in a 20km radius, provided there are "eyes on" the target to adjust fire. Artillery pieces are typically much more lightly armored, and slower than main battle tanks.
Tanks tend to move a lot faster and provide direct fire on an enemy working with infantry and/or as part of cavalry, aviation and other "maneuver units."
During the days of the US "Air-Land Battle Doctrine" the majority of Army officers making general came from the Field Artillery (i.e. Tommy Franks); the concept being they came up through the commissioned ranks with a "total battlefield" mindset in support of the other arms, who thought specifically in terms of the tactics of their branches.