Tank destroyers (also known as TDs for short) are specialized armored fighting vehicles designed specifically for destroying heavily armored tanks. They are represented by a green or red inverted triangle on the mini-map and over their respective target marker.
Tank destroyers vary widely from vehicle to vehicle, but they do share a number of things in common. Tank destroyers are generally the most well armed direct-fire vehicles in the game, though they still fall short of indirect-fire artillery. Many tank destroyers lack a turret, and instead mount their guns in the vehicle's hull. Turning the gun beyond a certain point in these vehicles requires turning the vehicle's hull (which in turn results in accuracy and camouflage penalties). These sorts of tank destroyers often have difficulty maneuvering to attack enemies around corners or turning to face flankers. Tank destroyers that do get turrets often get ones with limited traverse ranges or slow traverse speeds and are still prone to being flanked or circled.
How tank destroyers are played depends on the individual vehicle's strengths. Some tank destroyers, often nicknamed assault guns, are endowed with great amounts of frontal armor and can be played similar to brawling heavy tanks. Alternatively, there are many tank destroyers with little to no armor which are best played at a distance, using their camo values to stay concealed behind bush cover. From these positions, sniping tank destroyers can safely inflict damage with their high-power guns and ambush tanks who wander too far into the open. Many tank destroyers fall somewhere in-between these two extremes, with enough armor to withstand some direct fire but not enough to operate as a front-line brawler.
Variety and Examples
Though there may be many differences among tank destroyers, most of them are vulnerable to similar threats. Almost all tank destroyers are vulnerable to flanking maneuvers by fast enemy light and medium tanks. Even heavily armored assault guns are often poorly protected from the sides or rear and lack the fast-moving turrets needed to defend themselves from such angles. Fragile sniping tank destroyers not only suffer from these issues, but are also easy prey to anyone in range once their position is revealed. In addition, both the slow moving assault guns and the weak (and often open-topped) snipers are easy prey for artillery when caught out of position.