Great question, Ray. Meditation and hypnosis share some of the same brain wave states (alpha and theta waves) but there are quite a few variations of each, so I would generally call them different.
Hypnosis is a state of narrowed attention and increased suggestibility. Hetero-hypnosis is formally induced in a variety of ways, from confusion techniques to progressive relaxation. Self-hypnosis is also induced through an induction or protocol that the practitioner learns, but it can be as simple as taking three breaths and closing one's eyes, for an experienced practitioner.
Meditation can have a similar narrowing of attention, as one focuses on a particular thought or emotional state. Or it could be an emptying of the mind where one thinks about nothing at all.
Mindfulness is neither hypnosis nor meditation. Mindfulness is more about staying rooted in the present moment and acknowledging one's real time experience, without judgement or interpretation. You could choose to practice mindfulness with the help of a self-hypnosis or meditation protocol, but those are structures to assist the practice; they are not mindfulness itself.
Hope this clarifies things a bit.