Answer:
The difference is that the catholic church pyramid is more complex, having seven levels, from bottom to up: the laity, deacons, priests, bishops, archbishops, cardinals, and the pope.
The feudal pyramid is simpler, having three levels or estates: the nobles, the clergy, and the commoners. Some authors add a fourth level: the knights, which are above the commoners but below the clergy. However, the knights themselves were nobles, and even if many of them were low-level nobles, they can be still considered to be under the nobles estate.
The similarity is that both are hierarchical: social structures with a clear-cut separation of castes or classes of people, each level being subordinate to the one above and subordinating the one below.