Would the following two queries ever return different results? $($disregard ordering$)$

select PAT$\_$ID

from PATIENT

where

PATIENT.PAT$\_$ID in $($select PATIENT$\_$ID from MY$\_$CUSTOM$\_$TABLE$)$

$$

$$

Select PAT$\_$ID

from PATIENT

where

exists $($select null from MY$\_$CUSTOM$\_$TABLE where MY$\_$CUSTOM$\_$TABLE.PATIENT$\_$ID $=$ PATIENT.PAT$\_$ID$)$