A website usually supports many visitor goals; a sales funnel is usually organized around a narrower conversion path. Many businesses benefit from both.
What a website does well
A website can explain the brand, support navigation, publish resources, answer multiple intents and serve returning visitors.
What a funnel does well
A funnel limits choices and sequences information around one conversion objective.
When to use both
Use the website as the broad information and discovery layer, then route high-intent visitors into focused funnel experiences where appropriate.
Common mistake
Do not convert every informational page into a hard-sell funnel. Match the experience to what the visitor is trying to do.