HTIDE (Hirschian Torah Im Derech Eretz) is dedicated to all mitzvos, not just Torah study. It rejects the Medieval Spanish notion of mitzvos as handmaidens to the ultimate goal of philosophic understanding. This notion was influenced arguably by Aristotelian-Arabic philosophers. R' Hirsch's explanation of the meaning and symbolism of mitzvos helps to enhance our love for the mitzvos. Rather, mitzvos are an end goal themselves. (See 19 Letters, Letter 18).
Likewise, HTIDE rejects the exaggeration of and singular focus on the kabbalistic notion of Torah lishmah meaning Torah for the sake of study alone. It recognizes that this understanding was intended as a response to radical chassidus of the 18th century. It was not meant to replace the basic understanding of lishmah meaning not for self-aggrandizement but rather for serving Hashem and doing mitzvos.
HTIDE encourages us to study all of the Torah including Nach and Halacha, as the Gemara says we should.
HTIDE reminds us that Jews are supposed to care about all of humankind. We are not in it for ourselves.
The HTIDE person desires to contribute to his host country, to society as a whole.
The HTIDE person pays special attention to his personal conduct. If we need to look to the classier realms of gentile society for tips on this, so be it. "Derech Eretz includes everything that results from the fact that man's existence, mission and social life is conducted on Earth, using earthly means and conditions. Therefore this term especially describes ways of earning a livelihood and maintaining the social order. It also includes the customs and considerations of etiquette that the social order generates as well as everything concerning humanistic and civil education." R' Hirsch on Pirkei Avos
HTIDE welcomes all true advancements of human kind in the scientific or social realms, yet it examines Torah from within. It welcomes knowledge from the world if it fits into Torah, but does not synthesize Torah with external ideas.
While in Western countries, we conduct ourselves and maintain our homes and our physical selves with the orderliness and dignity that is characteristic of the West. This is a positive act, it is not a concession to goshmiyus. In the East, they suffered poverty, imposed upon them by dictators. There is no benefit to carrying over the results of that to America.
In AHTIDE, (American Hirschian Torah Im Derech Eretz) we have to be particularly careful in our selection of secular materials and our involvement with secular society. The amount of indecent and twisted material out there is extensive. Moreover, it has infiltrated all realms of society. In the old days, you had pool halls with pool hall type people and you had museums and schools with modestly dressed conservative people. Today, there's nary a difference between the two. So wherever you go, you have to exercise enormous care. One possible approach is to limit secular studies within the humanities to 19th century people or earlier. And early 19th century is better than later 19th century.
As Rav Breuer emphasized, Austritt goes hand in hand with TIDE. One understanding of that is as follows: once you open yourself to the outside world, you become vulnerable to its negative influence. Problematic groups even within Orthodoxy presumably all ready have allowed that negative influence to shape its core. Therefore, you need to avoid the problematic groups even with Orthodoxy because they have led the way in institutionalizing the bad of the outside world. However, in the 21st century we pretty much are forced to deal with other groups because the German community is so small. The same goes with the State of Israel. Half of Kelal Yisrael is there and the larger part of Orthodoxy is there. One pretty much has to work with it. This applies even more to the person who can't for whatever reasons live in Washington Heights. Then you really have to deal with the other groups. But even within Wash. Hts. you must deal with other groups because there are Haredim and Modern people there and likely few pure Hirschians. So Austritt today is a trickier business and requires tremendous self-discipline, particularly mental discipline, and, at the same time, more tolerance. You need more tolerance on the outside and more discipline on the inside.