Learn Spanish (Latin America): No hay diferencia; son igual de buenos. - There's no difference; they are equally good.

In the phrase igual de (equally), the word igual acts like an adverb, which means its form never changes. Even though the subject is plural, only the adjective after it changes to match (buenos). If you simply said son iguales, it would mean "they are identical," but igual de buenos means "they are equally good."

The lesson mentions using que with igual de, so why isn't there a que in this sentence?

You only need to use que (as) when you explicitly name the thing you are comparing against. For example: Son igual de buenos que los otros (They are as good as the others). Since this sentence just says "they are equally good" and doesn't state the other option, we drop the que.

Could I use tan instead of igual de here?

Yes, you could say son tan buenos, which means "they are just as good." Both structures are used for comparisons of equality. However, igual de buenos strongly emphasizes the exact equivalence ("equally good"), which pairs perfectly with the first half of the sentence, No hay diferencia (There's no difference).

What happens to igual de buenos if we are talking about feminine things, like two cameras (cámaras)?