If the rest of the details match,ie if they live at the address you know your relatives lived at,were the right age, etc then there is a probability that they are the same people. Census takers in the past usually wrote down the information themselves and sometimes names were mispelt, misheard or misread - so Nessie could become Jessie
. Likewise it is feasible that May
could be used as a nn for Marjory,but she would give her official name to the census taker.
I suppose the only way to find out is to try and trace Jessie
through another census, homeownership records,death certs,etc.