Height Increase can refer to increasing the height of anything. It can refer to increasing the height of a statue or a building. In regards to height seeker however it is all encompassing for any height increase methods. By adopting a spiky hair-do you are increasing your height, by wearing lifts you are increasing your height, and by surgically implanting silicone on the top of your head you are increasing height.
Growing taller as a keyword refers to specifically the act of growing taller by increasing the length of your bones via your growth plates. Technically, you are not growing taller by undergoing limb lengthening surgery, you are increasing height. Your bones are being broken and then healed, you are not per se growing. When you increase your height by getting a massage to help better align your spine you are not growing taller, you are increasing your height.
If you are a height seeker looking only for methods involving the epiphyseal growth plate then you should use grow taller as your keyword base and add some long tails for something specific. If you are a height seeker who is open to all methods to increase height then you should use height increase as your base search term plus long tails.
Now, let’s say you are an internet marketer targeting the grow taller/height increase niche. What does the keyword used to find your site say about the user? Height Increase is more grammatically correct. Your visitor may be a stickler for grammar and expect the same from your site. Someone who types in grow taller may be a person who is still undergoing puberty and is looking for ways to maximize and accelerate their growth.
The more specific the long tail, the more your visitor knows about the height increase niche. If your visitor types in grow taller by increasing bone length, your visitor must be pretty knowledgeable about science and existing height increase methods. You have to realize that some people don’t know basic anatomy and physiology. A person who just types in height increase may think it’s possible to increase height just by proper nutrition.
The same applies for other niches. For example, the weight loss niche could also be called the fat loss niche or the adipose tissue loss niche. Weight loss could refer to losing water weight and a searcher with that term could be relatively inexperienced in the niche. A fat loss seeker has more of a grasp on the basics of the niche. An Adipose Tissue seeker has an extremely strong grasp.
In conclusion, if their are two possible keywords for the same niche type you should carefully consider what keyword you are targeting and what the searcher is looking for by using the specific synonym.