The same geometry model. Two methods are used to calculate the displacement of the structures. The results are so different.

First method with the beam unit: 

-The same load:10000N

-Fixture: 4 joints

-Displacement 12.1mm

Second method with the solid unit: 

--The same load:10000N

-Fixture: 2 face

-displacement  23.6mm

Who can explain these?

Thanks!

Liu