I have not read "Disappearance" nor ACIM, so I shall not comment.
I have read "The Power of Now" and "Ask and It is Given". I really advise that you read them more carefully. In my opinion, the more you grasp their ideas, the more you will see that Abraham-Hicks and Eckhart Tolle are often talking about the same things, but using different terminology.
If you do any serious meditation at all, you will probably understand, in an experiential way, what both Eckhart and Abraham-Hicks are talking about. Otherwise it may be somewhat difficult to explain with words.
I hate to oversimplify, but just a few quick examples:
1. Eckhart tells you not to think negative thoughts at all. Whereas Abraham-Hicks tells you to only think positive thoughts.
2. Eckhart tells you that the part of your mind which he calls the "pain-body" is what is causing you all your anger, fear, worry, anxiety etc. Whereas Abraham-Hicks tells you that your negative thinking attracts into your life all the things that cause you all your anger, fear, worry, anxiety etc. You see, "pain-body" is just a term for "ingrained patterns of negative thinking".
3. Eckhart tells you that basically when you know how to stop thinking, you will discover the eternal source of joy and happiness that was deep inside you all along. Abraham-Hicks tells you that the Source of Wellbeing has always been there too, deep inside you.
4. Eckhart tells you that basically, it's all just illusion. Abraham-Hicks tells that it's all just vibration.
5. Eckhart consistently talks about (a) thought, (b) emotion, and (c) how the two interrelate. That's also very Abraham-Hicks.
If you really, really want to know the difference between Eckhart and Abraham-Hicks, this is it -
Eckhart tell you that this reality is illusion, and for many of us, a painful and difficult illusion. Eckhart then points you to something much more beautiful on another plane of consciousness, if you can access it. And you don't have to fear death, because the part of you that is really you is eternal, it doesn't die.
Whereas Abraham-Hicks tells you that this reality is fun, and joyful,
it is good to be here, and nothing needs to be painful or difficult, once you understand how your thoughts create your reality. If you know how, you can magically create whatever you want to create (it's also like illusion) ... and eventually, when you die, you can just go on to another plane of consciousness, and do it all over again. Because the part of you that is really you is eternal,
it doesn't die.