ORACLE 连接查询效率问题

如题：请问ORACLE的大牛们 oracle 连接查询的简单连接查询和标准的连接查询有和区别？简单的连接查询SQL：select
  t1.name, t1.age, t1.stuNo, t2.kecheng, t2.fenshu
from
  student t1, stuGrade t2
where
  t1.stuNo = t2.stuNo and t1.stuNo = '';
标准的连接查询SQL：select
  t1.name, t1.age, t1.stuNo, t2.kecheng, t2.fenshu
from
  student t1 [inner] join stuGrade t2 on t1.stuNo = t2.stuNo
where t1.stuNo = '';
小弟不是很明白其中有和区别，还望大牛们不吝赐教，告知一二~~~