convertion differences between Convert.ToInt32 and int.Parse

int.Parse("12") --> 12
int.Parse("12.12") --> Format Ex
int.Parse(null) --> Null Ex
int.Parse("889708888888899888888098980909089808990890890890900") --> overflow Ex

convert.ToInt32("12") --> 12
convert.ToInt32("12.12") --> Format Ex
convert.ToInt32(null) --> 0
convert.ToInt32("889708888888899888888098980909089808990890890890900") --> overflow Ex

int re = convert.ToInt32(Session["val"]); --> 0
int re = int.Parse(Session["val"]); --> ArgumentNULLException

int re = 0, res;
if (int.TryParse(re.ToString(), out res))
{ string fds = res.ToString(); }
else
{ string dfsa = res.ToString(); }

re = Convert.ToInt32(ViewState["fdsa"]); --> 0
re = (int)ViewState["fdsa"]; --> null reference exception, Object reference not set to instance of an object // it is fastest than all
re = int.Parse(ViewState["fdsaf"].ToString()); --> null reference exception, Object reference not set to instance of an object
--
Convert.ToString() handles the NULL
.ToString() throws the NULL reference exception