Trim is the catch-all term for the boards that finish off transitions around doors, windows, floors, and ceilings. Molding is a subset of trim—often more ornate—that adds visual flair where two surfaces meet. In other words, every molding is trim, but plenty of trim (like simple baseboards or door casings) isn’t considered molding because it focuses on function over decoration.
Painting trim before installation keeps drips off your walls and floors, but you’ll still need to fill nail holes and touch up later. Painting after installation eliminates most of that touch-up work, yet it requires careful taping to protect surrounding surfaces. Both options work; choose the one that best fits your schedule and comfort level with prep tasks.
Glue speeds up installation and skips the hassle of filling nail holes, but removal later can tear up drywall, and warped boards are harder to fix. Nails take a bit longer, yet they hold trim securely and make future repairs simpler. Most pros stick with nails for a durable, professional-looking finish.