I too used to get confused on the distinction between "littles" and "inner child" there are so many people and places that use the two interchangeably.

around here where I live and work the term inner child designates you feeling like a child while in a fully aware state of mind... you are in a mall and you are walking past "Santa's Station" and seeing all the children sitting on Santa's lap you remember how much you enjoyed going to see Santa and you remember that feeling so well that you fill with happiness from that memory.

there is a therapy technique that takes this a step further where a therapist has their client close their eyes and imagines that child they used to be during key points in their childhood. the therapist has the client say or imagine doing things to help that imaginary child that represents who they used to be.

alters (your word "littles") are more than just a feeling you get while fully aware. they have their own job/purpose, own way to be, and take control more than once to do what their job/purpose is and to live their own life separate from how you are and how you live your life. they may have some / a few things in common with you but who and what they are is separate from who and what you are.