European pension systems have multiple components. There is usually a minimum guaranteed pension based on residency alone, which is paid if you don't have enough income from other sources. That can be supplemented by a separate housing benefit.

The main component is usually something similar to US Social Security, except that contribution rates are higher (16% in Sweden). Benefit rate (at any given retirement age) is usually close to a linear function of total contributions, adjusted for inflation. Most people expect to get most of their retirement income from that component.

Then there are supplementary components, such as voluntary or union negotiated private pensions. Some of them are a bit weird, such as the Swedish defined contribution plan with a mandatory 2.5% contribution.