It is one of those need to read the label things, it gets confusing since there are foods that are called strictly Starter feeds or Grower feeds, and some companies make feeds in between the two, or use both names...The protein % is usually the big difference in chicken feeds, except for the high calcium % in Layer.
Chick Starter is usually formulated to meet the needs of growing chicks to about ten weeks of age and is usually around 20-24% protein.
Grower/Finisher is usually formulated to meet the needs of adolescent birds between 10 and 18 weeks / point of lay and is usually 15-16% protein.
However a lot of companies make a more general feed that can be called Starter/Grower and it is more of an all ages food, from baby chicks to pol, or even beyond if you offer oyster shell on the side, it is usually around 18-20% protein.
They also make things like Flock Raiser or All Ages type foods.
With your birds, it probably doesn't matter if you feed Chick Starter or Grower since they are adolescents, if the Chick Starter available is really high protein, you can feed them some scratch as treats to bring it down a little.