Main Difference
The main difference between Soffit and Eaves is that the Soffit is a structure to fill the space between the ceiling and the top of cabinets mounted on the wall and Eaves is a edges of the roof which overhang the face of a wall.
Soffit
A soffit is an exterior or interior architectural feature, generally the horizontal underside of any construction element. A structure to fill the space between the ceiling and the top of cabinets mounted on the wall is also called a soffit, as is the material connecting an exterior wall to the edge of the roof under the eaves.
Eaves
The eaves are the edges of the roof which overhang the face of a wall and, normally, project beyond the side of a building. The eaves form an overhang to throw water clear of the walls and may be highly decorated as part of an architectural style, such as the Chinese dougong bracket systems.
Soffit (noun)
The visible underside of an arch, balcony, beam, cornice, staircase, vault or any other architectural element.
Soffit (noun)
The top point of the inside open section of a pipe or box conduit.
“The elevation of the pipe soffit is 10.4 meters above mean sea level.”
Eaves (noun)
The underside of a roof that extends beyond the external walls of a building.
Soffit (noun)
the underside of an architectural structure such as an arch, a balcony, or overhanging eaves.
Eaves (noun)
the part of a roof that meets or overhangs the walls of a building
“under the eave and the window is a workbench”
“wild bees nest under the eaves”