I am not sure of the exact def. but Ill try my best.
Jismani remand is when a suspect is handed over to the concerned police station to be kept in the lockup to for questioning purposes and 'aid' in the investigation process. What this basically means is that for the period of Jismani remand, the suspect is kept in the lockup of the police station and IO investigates/questions him. You can very well imagine what happens then
Judicial remand on the other hand means that the suspect is remanded into judicial custody i.e. he is kept in a proper jail and can not be questioned/investigated any time or in any manner.
In short, judicial remand is more desirable from a suspect's point of view as it ensures (relatively) no torture on hand on police and following of rules/regulations and civil rights