Sentence

餅は餅屋。

(もち)餅屋(もちや)
Every man to his trade.
Sentence

餅屋は餅屋。

餅屋(もちや)餅屋(もちや)
A specialist has his own strength.
Sentence

もちはもち屋。

もちはもち()
Every man for his own trade.