Cold front and Cold spell

Cold front noun - The front of an advancing mass of colder air.

Cold spell and cold front are semantically related. in advancing front of colder air topic. In some cases you can use "Cold spell" instead a noun phrase "Cold front".

Cold spell noun - A spell of cold weather.

Cold front and cold spell are semantically related. Sometimes you can replace phrase "Cold front" with "Cold spell", this phrases are similar.