Mannahnin
Scion of Murgen (He/Him)
AC is sometimes a point off, as I recall, since AD&D sets unarmored AC at 10, and D&D has it at 9.Most of the key stats are completely mechanically compatible, HD, AC, damage, special attacks and defenses.
But yeah, generally speaking they're super close. The 1E MM is even closer, since it was really written as much for OD&D as it was for AD&D.