To the untrained eye, there is little visual difference between a Sturmgeschütz and a Jadgpanzer. They're both low, turretless tracked vehicles with a big gun. However, they were actually quite different. For example: a StuG IV is boxy box on tracks, intended to support the infantry and taken an occasional pot shot at an enemy tank. A Jagdpanzer IV, built on the same chassis, is designed as a dedicated tank hunter. It has a different internal lay-out, better rangefinders, sloped armour and a larger gun - that of the Panther, in fact. The Germans built a Jagdpanzer on the basis of every chassis they used, ending in the behemoth Jagdtiger.
The Nashorn had a good gun but little protection for the crew - the top was open (molotov cocktails!) and the side armor only offered protection against rifle bullets. It started life as the "Hornisse" but Hitler renamed it to "Nashorn", which on closer inspection is not a bad name. This one belonged to Albert "the Tiger of Vitebsk" Emst, who would later fight one of the few Jagdtigers...
This jagdpanzer was commanded by Rudolf Roy, who whould get his head shot off on the next day. The "Hitlerjugend" that he was part of, was intended to exploit the first breakthroughs in the Battle for the Ardennes. Which would have gone the Allies' way, even if Rudolf had survived. This illustrates the tank commander's conundrum: if you stick your head outside of the hatch, you can see better what to shoot at, but be prepared to lose your head.
At Kursk, sPzJgAbt 654 had 44 Ferdinands. That was one too few; the missing one was still on the test bench in Kummersdorf. These early Ferdinand were unreliable pieces of junk, and most of them just broke down. However, the gun was great. So they were not unsuccessful in the short time they were in service - many Russian tanks can testify to that.
After the battle of Kursk, the surviving Ferdinands were sent on to the Nibelungenwerke factory in Austria where they were converted into Elefants. That means: extra armour, a ball mounted MG, Zimmerit and a cupola. Also, the silliest rifle in history: a StG44 Krummlauf. sPzJgAbt 614 was equipped 4 remaining Elefants and added to Kampfgruppe "Ritter" near Zossen, to the south of Berlin. They uselessly defended the city against the approaching Russian army.
Kompanieführer Oberleutnant Wolf-Dieter Lützow's Hetzer. 551 was part of the massive retreat of Armeegruppe Nord after the failure of the siege of Leningrad. The German army fought with the usual conviction and expertise, and the Russians suffered heavy losses. However, they could afford these losses, which was not the case for the Germans. PzJgAbt 551 came to Tulkincia in a particularly dangerous situation - they were threatened with yet another encirclement - and had to be liberated by the tanks of Panzer-Regiment Großdeutschland.
On 30 July, the Jagdpanthers of 654 were lying in ambush, something for which the Normandy bocage was exceptionally suitable. Within minutes they were able to take out a dozen Churchill tanks from the British 6th Guards tank brigade before being chased away by tanks from the same unit.
"Heavy tank hunter division 653" fought its way back from Italy, to the Ardennes and operation Nordwind. There, remnants of the Wehmacht tried once more to cut of the American supply lines - to no avail. After this, the division went to Austria where it joined the 1st and was one of the last units in the war to surrender.