This is an explanation of the differences from FindLaw:
Probable Cause for Arrest
Probable cause for arrest exists when facts and circumstances within the police officer's knowledge would lead a reasonable person to believe that the suspect has committed, is committing, or is about to commit a crime. Probable cause must come from specific facts and circumstances, rather than simply from the officer's hunch or suspicion.
"Detentions" short of arrest do not require probable cause. Such temporary detentions require only "reasonable suspicion." This includes car stops, pedestrian stops and detention of occupants while officers execute a search warrant. "Reasonable suspicion" means specific facts which would lead a reasonable person to believe criminal activity was at hand and further investigation was required.
Detentions can ripen into arrests, and the point where that happens is not always clear. Often, police state that they are arresting a person, place him/her in physical restraints, or take other action crossing the line into arrest. These police actions may trigger the constitutional requirement of probable cause.
Someone arrested or charged without probable cause may seek redress through a civil lawsuit for false arrest or malicious prosecution.
Probable Cause to Search
Probable cause to search exists when facts and circumstances known to the officer provide the basis for a reasonable person to believe that a crime was committed at the place to be searched, or that evidence of a crime exists at the location.
Search warrants must specify the place to be searched, as well as items to be seized.
There are many instances where a search warrant is not required. Common situations in which police are allowed to search without a warrant include:
when they have consent from the person in charge of the premises (although who that person is can be a tricky legal question);
when conducting certain searches connected to a lawful arrest; and
in emergency situations which threaten public safety or the loss of evidence.
Police also do not need a warrant to search or seize contraband "in plain site" when the officer has a right to be present.
Probable Cause to Seize Property
Probable cause to seize property exists when facts and circumstances known to the officer would lead a reasonable person to believe that the item is contraband, is stolen, or constitutes evidence of a crime.
When a search warrant is in play, police generally must search only for the items described in the warrant. However, any contraband or evidence of other crimes they come across may, for the most part, be seized as well.
Should evidence prove to have resulted from an illegal search, it becomes subject to the "exclusionary rule" and cannot be used against the defendant in court. After hearing arguments from the prosecuting and defense attorneys, the judge decides whether evidence should be excluded.
http://criminal.findlaw.com/criminal-rights/probable-cause.html