bold building names

From your follow-up question I imagine this is due to the mapnik render. I presume that you have tagged some buildings on the university campus with amenity=university. Mapnik's render rules are biased towards showing large campus sites at fairly low zoom levels and use bold text. You may find these buildings are much more visible than adjacent suburbs, towns and villages.

Basically its not good practice to tag individual buildings with amenity=university except when they are isolated. (See for instance this question: should-all-buildings-at-in-a-university-campus-be-tagged-amenityuniversity). Instead map the campus as an area and tag the buildings with building=*, where '*' can be values such as yes, laboratory, residential_hall. Use taginfo or tagwatch to look for widely used values.

No. There is no concept of "approved" in OpenStreetMap.

OpenStreetMap is, at heart, a vast database of geographic information - not a map.

Each particular map "rendering" is free to pluck out different pieces of information from the database, and show them in different colours. You can see this by using the '+' layer switcher (at the top right) on the main openstreetmap.org website, and flicking between 'Mapnik', 'Osmarender', and 'Cycle map' styles; all three take the data from the same database, but they've chosen to show different items in different styles.

It sounds like the style you're looking at is choosing to render buildings with one set of "tags" in a different way to those with another. Zoom into an area with both, and click "Edit". Then, click on the items in question. You might well see that one, for example, is tagged as a tourist attraction and the other as a house, or something. (For an in-depth view of the exact tags being used, click the 'Advanced' link in the editor.)