Yes, that is all about terminology. Let's say one morning, I decided to go for a market (which is a couple of blocks from me) to buy a ... fresh wild salmon, for expl. (then you put it in a glass bowl + salt + one shot of wiskey, wait for three hours, then a piece of bread + butter + slice of salmon, mmmm..., but this is the other story). Having come there I realized that there are just 5 sellers with 5 fresh wild salmons and 10 guys like me looking for them (high demand). So, who is raising price, buyers or sellers? I would say sellers (not me, I want to buy cheaper), so they are in control, right? However, on the other hand, I want salmon so desperately, that I am ready to give the higher price than other guys. From this position (more buyer than sellers), you could say that buyers are in control of the market (= in control of the prices?). This is a textbook's variation. However, they are not, they do not and can not control prices. So, in my humble opinion, termin "in control" is not appropriate, because it is confusing. But the rest are simple and understandable: high/low demand/supply and more buyers/sellers, so let's go with that.