See the following two images.
I think that the two orbitals should not resemble each other because s and p orbitals overlap in different fashions in the two cases.
In the case of sp hybrid orbital, both s and p orbitals are centred at the same point. As a result, s orbital does constructive interference with one lobe and destructive interference with another lobe of p orbital.
But in the case of molecular orbital, s and p orbitals are centred at different nuclei (and those nuclei can't be at the same point). Then how come the resultant molecular orbital resembles the sp hybrid orbital?
The right lobe of the molecular orbital should get enlarged due to constructive interference of s and p orbitals, but why does the left lobe get diminished? Shouldn't it remain as it is in the p-orbital?