No, they are not. There is a different lectionary cycle for Byzantine and Latin Churches as well as for Chaldeans, Maronites and the other oriental churches.

In the Latin church there is a further division between communities that use the 3 year lectionary cycle, and communities that use the pre-conciliar one-year cycle.

In the Greek Churh there is an additional division between those that use the modified Julian calendar and the old Julian calendar which (for now) is 14 days behind the Gregorian caledendar.

This next sunday you could attend 7 different parishes and here seven different readings, one-year Latin, three-year latin, revised Julian Greek, old Julian Greek, Chaldean, Maronite, Armenidan, Syro-malabar, Coptic.

Every few years we are all in sync celebrating Easter on the same day… but there will be variations in which readings are heard.

In the Roman liturgy, we read John 1:29-34 how John the Baptist knew Jesus as the one sent after him who ranks ahead of him.

Completely ignorant here, the Greek and Roman calendars are not the same?