The Romulan disruptor rifle went through a few changes. In 2368 their rifle was small and thin. By 2371 the rifle had been enlarged and given a much sleeker design. (TNG: "Unification I", "Unification II"; DS9: "Improbable Cause"). By 2387 it had been modified with a more conventional shoulder-braced configuration.
The Cardassian disruptor rifle was a much simpler design than the Starfleet Type 3 phaser rifle. It had very few settings on it and fewer components than its alien counterparts. The weapon's output rating was 4.7 megajoules, with 3 millisecond recharge rate and 2 beam settings. Major Kira Nerys said that it could be dragged through the mud and still fire. (DS9: "Return to Grace")
The Cardassian disruptor rifle was first seen in "The Homecoming".The description Major Kira gives that the Cardassian rifle can be dragged through the mud and still fire is an allusion to the Russian AKM, or Kalashnikov, which is well known for its reliability against the elements.