Differences between If and IIF in VB. NET

Let's take a look at the differences between the two functions.
1.   Private   Function geteachqty () Function Geteachqty ( Byval OBJ As   Object ) As   Integer
If   Isdbnull (OBJ) =   False   Then
Return Convert. toint32 (OBJ)
Else
Return   0
End   If
End Function

2.   Private   Function geteachqty () function geteachqty ( byval OBJ as Object ) as integer
return IIF ( isdbnull (OBJ ), 0 , convert. toint32 (OBJ)

End Function

Same, different, same, different ........

I think it is different. Based on my test results, I guessCode2 closer to code 3

3.   Private   Function geteachqty () Function Geteachqty ( Byval OBJ As   Object ) As   Integer
Dim Resule As   Integer = Convert. toint32 (OBJ)
If   Isdbnull (OBJ) =   False   Then
Return Resule
Else
Return   0
End   If
End Function

If I guess it is true, then the IF and IIF are essentially different and cannot be exchanged at all. You must be careful when using them.