Nearby is the list of all birds in the last ~5 years that have a valid eBird sighting within the specified search distance. Use the Nearby list to see what is around the location throughout the entire calendar year.
Recent includes those birds that have been seen in the specified search distance AND in the specified timeframe (1, 2 or 4 weeks). Use recents to catch up on what other people are seeing and reporting.
Month shows sightings over the past ~5 years during the specific months you selected. Use the month filters to plan a trip and see what you can expect when you are there. This is also excellent in areas with limited eBird data, as it relies on many years of data, rather than just data recently submitted.