A Church is those gathered around their bishop(s), celebrating the word and sacraments. Lutheranism is an ecclesial tradition, though not all Lutheran churches are in communion. (Like, say, Byzantine christianity is an ecclesial tradition, though not all Byzantine churches are in communion.)
If you want to find out what any given Lutheran believes, find out what Church he is part of. I akm part of the Church of Norway, and I am thus not obliged to answer for what, say, some WELS Lutheran should happen to believe.
The Roman Catholic Church is itself a union of 23 particular churches.
And the Roman Catholic Church recognises the particular Eastern Orthodox churches as valid and Catholic. Thus you do not have to be in communion with the Roman Pontiff to be Catholic, according to Roman Catholic theology.