1) The second one is more explicit about which columns are returned. The value of the 2nd one then is how much you value explicitly knowing which columns come back.
2) This involves potentially less data being returned when there are more columns than the ones explicitly used as well.
3) If you change the table by adding a new column, the first query changes and the second does not. If you have code like "for all columns returned do ..." then the results change if you use the first, but not the 2nd.
