A landing page has one job
A landing page focuses on a single action such as requesting a quote or booking a demo. It removes distractions, which is why it works well for ad campaigns.
A website builds trust and search visibility
A full website explains who you are, lists services, shows proof and helps you rank in search. It is where visitors go to check that you are real before contacting you.
How to choose
If you are running ads for one offer, start with a landing page. If you want long-term search traffic, credibility and multiple services, build a website. Most growing businesses eventually need both, and they should share a consistent brand.