In sonnet 18 Shakespeare uses the type of love that is young love. A quotation that backs up my explanation is ” shall I compare thee to a summers day.thou art more lovely and more temperate “. This quotation shows that Shakespeare does not want to compare his love for the person  he was writing about to one day of summer.in sonnet 73 Shakespeare uses the type of love that is old love that will always be there.a quotation to back up my explanation is “when yellow leaves, or none, or few, do hang ” and as the death bed whereon it must expire”.The first quotation suggest that the love the love that they had was old(because when yellow  leaves or none hang the tree is going to die,)in this quotation the tree represent  the love.in the second  quotation Shakespeare uses word that refer to death which gives us a sense that the love is going to die.