The overground are more traditional trains as opposed to the metro style for the Underground. Overground is more of a ring around central London - it's useful for avoiding going via central London if you don't want to.

The primary difference between the London Underground (the "Tube") and the London Overground lies in their geography, history, and the types of trains used. The Underground is the world's oldest subterranean railway, primarily serving central London with deep-level and sub-surface tunnels; its lines are color-coded (like the red Central or blue Victoria lines) and use smaller, specialized trains. The Overground, established in 2007 and represented by the orange double-line (now divided into six named lines like the "Lioness" or "Mildmay" in 2026), primarily serves outer London and forms an orbital loop around the city. It uses larger, "mainline" style trains that resemble commuter rail more than traditional Tube cars. While both systems are managed by Transport for London (TfL) and use the Oyster/Contactless payment system, the Overground operates on tracks that are often shared with national rail freight and passenger services. Additionally, because it is "overground," it offers much better mobile phone signal and scenery compared to the deep Tube. The Overground was created by linking older, under-used rail lines to provide better connectivity for the "suburban" areas of London that were historically underserved by the central Tube network.