Something not everyone is familiar with is that there are lots of different styles in dancing. Unless you have studied dancing or have an eager interest in it, you may have difficulty in telling the different styles apart. For someone that does it for a living it might seem obvious, but to many people it can be confusing.
It is best to look at each style individually and watch different dancers doing that style. You will see that even though they may not use exactly the same moves, there will be many things that they have in common with other practitioners of that style. Look at another style and again look at the things different dancers and groups have in common. Now put the two different styles side by side and you should be able to tell the difference.
Different dance styles can also have different music styles associated with them. Some may be danced to Irish music, others to 70s songs and others to Bollywood music.