Approximately 10,000 years ago a massive star in the constellation of Cygnus the Swan went Supernova. The explosion created a roughly circular ring of remnants and shockwaves which is called the Cygnus loop. The filaments of heated gas glow and appear brighter than the surrounding material.
Three of the brightest complexes are the Bat Nebula (AKA NGC 6995; AKA the Eastern Veil), the Witch’s Broom (AKA NGC6960; AKA the Western veil) and the Pickering’s Triangle (AKA NGC 6979). These three photographs were taken using filters designed to enhance the glowing filaments of hydrogen: red and blue.
Why so many different names? Because catalogue names are boring, and it all depends on how you look at things.