The four words below can be placed into two groups of two each - according to a certain pattern. 

1. KISS

2. NAME

3. EACH

4. LEAF

 

Answer:

 

The two groups are:

KISS and LEAF

NAME and EACH  

 

KISS and LEAF become new words if their last letters are moved to the front:

SKIS and FLEA

 

NAME and EACH become new words if their first letters are move to the back:

AMEN and ACHE