"Estaban cocinando" versus "cocinaban"?

[createdamadman]

I just read the phrase "estaban cocinando" in a story, meaning "they were cooking", and I couldn't help but wonder if one could simply use the word "cocinaban" instead?


For better context, the sentence is "Cuando llegamos al acampamento, los guías estaban cocinando la cena".


I know that "cocinaban" can also mean "used to cook" or "would cook", and "estaban cocinando" could not be used to mean either of those. But in the case of meaning "were cooking", I feel like the terms are interchangeable. Is this true or is there a difference I don't understand?