"Lo voy a colocar en tu maleta."
Translation:I am going to place it in your suitcase.
They have similar meanings but no. If you say poner it means you will put the object anywhere in the suitcase. If you say colocar it means you will place the object in a specific place in the suitcase so it won't create a mess.
I hope that clears your doubts.
I don't pretend to know DL's intent; however, for me, as a beginner, it is much easier to learn "voy a [any infinitive] than to learn the future tense for every verb. I will focus on learning pure future tense after I can express myself in past and present - and by then I will be studying more advanced courses than is offered in DL.
A previous commenter answered this question, so I'm answering using their knowledge and not necessarily out of my own personal experience--the difference seems to be that "colocar" means something is being placed in a specific location whereas "poner" means it's just being thrown in your suitcase, in a sense. I'd see this as the difference between the verbs "put" and "place" in English.
Using "case" is more logical.
I think it is odd that a "suitcase" can contain many other types of clothing and may never have had a suit inside it, but we don't say "dresscase" or "clothingcase".
I do have a briefcase, but it has never contained underpants nor legal documents.
Incidentally, "maleta" can also mean "bag" (though I don't know whether "bag" is accepted by DL).