Sounds quite different to me and this is kind of a reach. There's like million songs that repeats certain words.
Is Work From Home a copy of Work Bitch/Work because it says "work work work work"?
Yes (except that Work From Home was recorded before Work was released). But if the same artist released Work Bitch/Work and also Work From Home then I'd consider that a rehash. I mean, people call Work From Home a rehash of Worth It just because they're both about sex and feature a rapper, even though they sound nothing alike.