Understanding the formation and evolution of galactic structures, particularly bars and boxy/peanut-shaped (b/p) bulges, is crucial for comprehending galaxy dynamics. However, it remains unclear why certain galaxies develop a bar structure while others with similar mass and morphology do not. To address this, we use the TNG50 simulation from the IllustrisTNG project to explore the formation of a sample of barred galaxies compared to a similar sample that did not form a bar. Our analysis goes through major questions such as how does the presence of the bar affect the host galaxy and how efficient are the stellar disc instability criteria. Additionally, we investigate the formation, evolution, and buckling events of b/p bulges in barred galaxies using the Auriga simulations.