Lingual Orthodontics
These are Orthodontic brackets fixed on the the inner side of teeth. i.e.lingual side. This makes the brackets invisible when ones smiles.
Aligners
Aligners are a set of custom-made teeth trays that fit snugly over the crooked (crowded, spaced, malaligned) teeth to fix them. This is a relatively new technology compared to braces that are visible as wires on the teeth.
Invisalign stands for invisible aligners that are aesthetically pleasing and relatively comfortable for the patient during treatment.