I've read an article where it was said that Te users want to impact the outside world, while Ti users want to understand it, is that true? I see Te described as wanting accomplishment and external organization, while Ti wants understanding and internal organization of ideas, would you say this is a good differentiation?
Yeah, that's a fair assessment.
TJs shape reality by capitalism mostly, and then taking what money they earn and giving it back to humanity or a personal cause (ideally, obviously there are a lot of selfish SEOs). Ti shapes reality through innovative thinking and unusual approaches, which push technology further, and then have a desire to contribute to the general welfare of the world (ideally, obviously not always the case).
One difference is that they see success through different metrics; for a Te user, success is... units sold, awards won, achievements that you can track in some way. To a Fe user, success is "people like this," "it has made a difference," it has become popular, people agree it is good, etc. Even in TP types, success is still popularity / acceptance / external people impacted by the thing in a positive way.
For example, James Cameron (ENTJ 3w4/136 IMO). When people criticize the writing of Avatar, he says it's good enough to earn a billion dollars. Money = value in his mind. Not "it emotionally affected people and they liked it" (Fe) but "I earned more money with it than you will ever see in your lifetime." Interesting, eh? People can't really argue with that, since it proves his case -- it was good enough to make bank.
And yet, the writing is still pretty subpar. But does that even matter, when it rakes in several billion dollars? In Hollywood? No.