翻译成英文“各个学校的教学方法有很大差别

There is big difference of teaching manner among schools.

there is a big difference in the teaching method between each school

there are big differences in teaching methods of different schools/colleges/universities.

各个学校的教学方法有很大差别

There are big differences in the teaching methods among different schools.

different school has great different teaching meathods

There is much difference among the teaching methods of different schools