You are probably familiar with terms like Greek Orthodox, Russian Orthodox, Romanian Orthodox, etc. Now you have another one to add to the collection: Antiochian Orthodox.
What is the difference? In an important sense, there is no difference!
All of these belong to the one Orthodox Church. Each group has a relationship with the others that we refer to as "being in communion." We share the same faith, the same sacraments, the same over-arching tradition of worship; and, most importantly, we recognize each other as being part of the true Orthodox Church. Thus, if a member of a Greek Orthodox parish was to visit an Antiochian Orthodox parish, he would normally be allowed to recieve the sacraments, such as Holy Communion, while visiting.
In those countries around the Mediterranean and Eastern Europe where Orthodoxy is the religion of nearly all Christians, you would not speak of yourself as being "Greek Orthodox" or "Russian Orthodox" and so forth. You would simply be an Orthodox Christian. However in America, the Orthodox Church has arrived through missionaries and immigrants from a variety of traditionally Orthodox countries, who formed communities of the faithful that, at least for a time, needed to worship in their native language. For this reason, such qualifiers as Greek or Russian or Antiochian are used in reference to the ethnicity and language of the parish's founders. Naturally, when immigrants arrived on American shores, they looked to the Church leadership of their home country to send them priests who could minister to them in their native language.
For this reason, multiple Orthodox jurisdictions currently co-exist side-by-side in America, each under the care of a "mother Church" in a traditionally Orthodox land. Historically speaking, this is an unusual situation, and everyone generally agrees that eventually the Orthodox faithful in America should be united clearly in a single jurisdiction. Thankfully, the Standing Conference of Canonical Orthodox Bishops in the Americas (S.C.O.B.A.) exists to give concrete expression to the fact that the various Orthodox in America -- be they Greek, Russian, Serbian, etc. -- are all part of one, undivided Orthodox Church.
Holy Trinity Orthodox Church belongs to the Antiochian Archdiocese. The Antiochian Archdiocese is a part of the ancient Patriarchate of Anticoh in the Middle East. Today, the Antiochian Archdiocese is one of the most evangelically oriented of the Orthodox jurisdictions, with numerous parishes and missions throughout North America, and more being formed every year. The Antiochian Archdiocese has a strong commitment to bringing the richness of Orthodox Christianity to the people of America.
