A full-service (360) agency handles every area of brand communication in one place: from strategy and visual identity, through the website, to campaigns and printed materials.
The 360 model makes one promise: you don't coordinate several vendors or re-explain your brand to each of them. One contract, one team, one point of accountability for consistency. At large agencies that promise has a price: a heavy structure, account managers in the middle, and rates that keep the structure running.
There's a second variant of the model on the market: a boutique studio with a network of trusted specialists. A small team leads the core of the project (strategy, design, code) and coordinates specialised work – say, a photo shoot or a media campaign – with proven partners. You still get a single point of accountability, just without the cost of a big structure.
For buyers: instead of asking "do you do everything?", ask who exactly will run your project and which capabilities the agency has in-house versus buys in. The answer tells you more about the future collaboration than the service list on their website.