Severity: How severe (the effect of the bug on the 
application) the bug? 
1 - High
2 - Medium
3 - Low

Priority: The time to fix the bug based on the severity and 
type of thebug
1- High (within 24 hrs)
2- Medium
3- Low

I tell you the difference of severity n priortiy

The tester will find the bugs n sometimes the bugs will be 
found by the customers, whatever bugs have been found given 
some severity like how much impact the bug is giving on the 
particular module n the functionality if its seviour bug 
its S1 n little fine its S2 like that.....

comes to the priority, when the developer gets the bugs he 
just look into the code and the impacted area if he feels 
its giving high impact to the rest of the functionalities 
its given P1 or little low its p2....p4 n so on...

I hope this is the answer of the severity n priortiy

still have doubts contact me

severity is the hype that would be created by the defects  
i.ehow much it would be effecting in further processess..
Priority is how important is that to rectify the BUG and 
whether we can further move with the process without 
rectifying tht under present situation.

Severity nothing but it may effect on function of the 
build...it modified by developers as early possible depend 
on SEVERITY(High,Medium,Low)..Priority nothing but It not 
effect on functionality that means it belongs to non 
functional testing....It is also fixed by developers as 
early as possible depend upon the PRIORITY
(High,Medium,Low)......

Severity is in terms of Application
And priority is in terms of Requirements

severity and priority do come up with bug tracking.

Severity is the state being served according to the product.
Assigning Severity for a bug is straightforward, Using some 
general guidelines about the project,testers will assign 
Severity.

Priority is associated with scheduling.Priority means 
something is afforded prior attention.

Severity of the bug is one of the factors for assigning 
priority for a bug.  Other considerations are might be how 
much time left for schedule, possibly ‘who is available for 
fix’, how important is it to the business to fix the bug, 
what is the impact of the bug, what are the probability of 
occurrence and degree of side effects are to be 
considered.

"Priority" is associated with scheduling :Means which bug 
is going to be fixed first with respect to CUSTOMER point 
of view

"Severity" is associated with standards,how the bug affects 
the application with respect to FUNCTIONAL point of view of 
the product

Note :Category and Nominclature of the priority and 
severity totally depends on the Organizational strategy.
   Example : Some Company follow : P1, P2, P3
             Some Company follow : High, Medium, Low