They don't have anything to do with each other.
401(k) is a retirement savings plan. It allows americans who are 21 years old and up to self contribute a certain amount of money per year [adjusted each year] in a tax deferred way. That is, the owner wouldn't pay income tax on the money [this year], but would pay income tax in the year it is taken in dispersement [say, 2050]. Presumably, one's income will be lower per year after retiring than while actively working, so therefore, the tax percentage rate would also be lower, therefore saving some tax money. The money is placed into, basically, the stock market.
A recipient is declared for a retirement plan, as to who would get the money if the owner dies, but that is not life insurance. It's just money in an untouchable account [although withdrawals CAN be made under certain circumstances, there are extra tax penalties if one does].
These sound like divorce questions.
Retirement plans are owned solely by the contributor. Each spouse, if filing jointly, could maintain their own IRA if their employer doesn't offer a retirement plan, also subject to the annual deferral limits, but that can be done through a bank or investment firm. If a divorce attorney is trying to portion money that is already in a retirement account, that sucks. Get your own attorney to detail all the info with you if so.