How is "if one does not differ" translated using the word 異なる and the ば-ending?

Question

異なる is the dictionary form. To express the idea of condition, one has to change the u into an e and add the suffix ba.

異なれば = If one differs.

How do you express the idea of a negative condition -> if one does not differ?

Answer 1

"if one does not 'verb'" can be expressed as : verb + ない form + ば form = verb + なければ

It is similar to the ば form conditional for い adjectives: 高い(い adj) + ば form = 高ければ

In your particular example : 異ならなければ