How to distinguish between American Indians and Indian Indians in native English (language) parlance?
Can I say Indian Indian to say Indian from Asia compared to the Native Americans?
"Native Americans" is the preferred term. These days it's less common to refer to them as "American Indians" or "Indians". However that isn't to say that they don't refer to themselves as "Indian" or use their own, tribal name (like Lakota, Sioux, etc.).
Nevertheless, I suggest you use "Native American" when referring to people from that ethnic group, and "Indian" when referring to people from India (although, sometimes we are forced to say "Indian from India" to clearly distinguish what we mean).
If this sounds confusing, it is. In the multicultural mix that is the United States, it's often difficult to know the exact term to use that won't cause offense to any particular group.
If your meaning of "Indian" is clear from context, you can use "Indian".
If you need to be more specific, you can use:
If you need to be more specific, you can. For example:
There are a couple of ways to do this with varying degrees of political correctness.
Saying "India Indian" to clarify, is one of them. Note, "India", not "Indian" as in your question. I've certainly used this before. This is probably between the following two on the "appropriateness" scale. It's less formal than the second option and more than the last.
You could also refer to the part of the globe, typically "South Asia", so you could say "South Asian Indian". This would be a very correct and proper way of saying it and doesn't have the repetitive nature of the previous version.
If you're less interested in "proper" and you say it with a smile, you can do what they did in Good Will Hunting and say "Dot, not feathers". This is questionably appropriate as it runs the risk of making you look bad but, personally, I find it amusing. Not everyone may agree. Regardless, this is very informal.
At some point in the future it may be more normal to be understood to mean "someone from India" when you say "Indian", but for now, there still tends to be confusion as we're transitioning away from "Indian" towards "Native American" or "First Nations".
This is actually a question native speakers (particularly in the USA) struggle with. Often times, you have to rely on context.
There are some who say that you should use the term "Native American" instead. Some of the people who will tell you that are Native American themselves.
However, Native Americans are divided on the subject (as Robusto mentioned in the comments). Many quite proudly prefer the term "Indian".
For people from India, sometimes you will hear people say things like "dot, not feather" to disambiguate, but that's so informal I wouldn't suggest being the first person in the conversation to do it (unless you are one of the two ethnicities in question). The other term I've heard is "Asian Indian". The third thing I've seen people do is contort the sentence to identify the person's heritage geographically, rather than ethnically. eg: "His parents are from India." or "of Indian extraction".
The best advice for what to call indigenous Americans I've seen is what my sister, Osage anthropologist Jean Dennison set down in the introduction of her book Colonial Entanglement*. I'll try to get an exact quote later, but IIRC her rule was basically:
* - shameless plug
This by no means an authoritative answer, just my personal experience:
It is clear to me that Native American is widely understood to mean descendant of the indigenous people of the Americas and doesn't have the confusing connotation with India.
So, where possible, I avoid using Indian for people from the Americas altogether.
But I have visited the USA and Canada several times in the last 2 years and had the opportunity to ask the locals in person which term they preferred.
Seems that both in the USA (Nevada, Utah, Arizona) and Canada (Vancouver Island, British Columbia area) every single Native American I asked (and I asked at least 30 people) preferred the term First Nation.
The term is also seen frequently in museums and tourist guides. (Far more than Native American.)
I got the distinct impression that Native American might be politically correct, but not to the Native Americans themselves.
As I understand it it is mainly a sort of group-identity thing: the First Nations people consider "Native American" a designation foisted upon them by others, while they consider "First Nation" (we were here first) as more their own designation for themselves.