A hybrid generally speaking is a cross breeding between two different strains. The resulting offspring are referred to as a hybrid.
The term hybrid is often used to describe a ratio of indica to sativa. In terms of genetics, hybrid has nothing to do with indica/sativa ratios.
So what’s a clone? A clone is the asexual propagation of a specific plant. It’s a method to preserve and propagate a specific plant instead of germinating seed stock to find plants to grow. Clones are derived initially from individuals that are germinating and breeding plants. An individual could germinate 1000 seeds and find one exceptional plant that exemplifies the strain. The plant that the breeder found is a very rare plant. To keep this plant alive, they will clone it. Cloning preserves that special plant. Clones make up a majority of what is seen in the market today. Exceptional clones, found from seed, are being passed around and distributed.
The quality of some of these clones will vary tremendously depending on the individual that found it. One grower might germinate 10 seeds and keep their best female. Alternately, an individual could germinate thousands and have a better chance of finding those rare plants. It’s similar to playing the lottery – germinate some seeds, grow them out and see if you hit the jackpot. When you see clones, it means someone has already done the work and found that exemplary plant.