Is heptathlon for women only and is decathlon for men?

Answer 1

At the Olympic level yes but technically no. Women do compete in the Decathlon but not (yet) in the Olympics. With an age grading factor included, the highest point total ever is by masters athlete Nadine O'Connor. And indoors the men compete in a different heptathlon. I suggest these are evolving situations as it has taken decades to reach acceptance (into world championship and Olympic level events), but women outdoors and men indoors have advanced from pentathlon to heptathlon and continue to test further bounds. There is even an icosathlon (double decathlon).