Difference between GeoJSON and TopoJSON

Question

What is the difference between GeoJSON and TopoJSON and when would I use one over the other?

The description of TopoJSON on GitHub implies the TopoJSON files are 80%

Answer 1

It depends on many considerations. Among them are the following:

1) The nature (data model) of the feature or features you'd like to represent 2) Any attributes you'd like to have associated with those features 3) How you'd like these features to behave on the page (static vs dynamic)

However, this is a tough question to answer in the abstract. Regarding some specifics, if you have a contiguous polygon coverage or another situation where features are sharing boundaries, topojson's model allows you to exploit the redundancy and factor that into the model.

Read the documentation, dissect examples (e.g, bl.ocks.org), and then get some data and represent it in both geojson and topojson and create your own visualizations.