In the United Kingdom there are two types of allotments. The traditional ‘allotment’ and ‘leisure gardens’.
Allotments can be run either by the local authority or privately owned. There is a set of rules such as size of shed but the owner must grow more vegetables/fruit than flowers. This dates back to the original allotments act. Some boroughs state what the percentage is but usually it’s around 80% food over decorative flowers.
These can also be run by either local authorities or privately owned. They also have a set of rules regarding shed size but the difference is shown when it comes to the use of the land. You are free to grow whatever you like without working towards a percentage of vegetables/fruit to flowers. You can have an entire plot of flowers if you wish. They are more like the traditional garden you would find attached to a house.