ジョンさんの　生年月日と　わたしの　生年月日は　おなじです。
John's birth-year, month, and date and my birth-year, month, and date are the same.

→ジョンさんと　わたしの　生年月日は　おなじです。
John's birth-year, month, and date and mine are the same.

→ジョンさんと　わたしは　おなじ　生年月日です。
John and I have the same birth-year, month, and date.

1/2と　0.5は　おなじです。
1/2 is the same as 0.5.