Yes, a 401k is one type of DC pension. Specifically, one subject to various stipulations of the tax code section 401(k), where an employer has to setup the plan in such a way that sufficient employees benefit from it in sufficient amounts to pass the non discrimination testing. In exchange, the income contributed is not taxed until it is withdrawn after retirement age.
A Roth 401k is the opposite, where the income contributed is taxed today, but the withdrawals are not taxed after retirement age (unless politicians change their mind in the future...)
An IRA (individual retirement account) is similar to a 401k, except it involves no employer, and the amount of income that can be contributed pre tax is much less, and maybe zero if you earn too much in a year.
A Roth IRA is like a Roth 401k.