How are a bridge and an isthumus alike and different?

An isthumus and a bridge are alike because both cross over a body of water, and both are something that can let us walk over that body of water

Water flows along the east coast and across the western tropical pacific towards south america, while they both are directed towards that way,  el niño does not directly affect the southern flow of water along the coast. 

Their neck becomes more flexible allowing for a better view of vision. legs become stronger for running