FLV (Flash Video) is a video container format developed by Adobe Systems and comes with a .flv filename format. FLV is primarily used to stream audio, video, and text data such as subtitles on sites like YouTube, Metacafe, and more. It supports MPEG-4 Part 10 (H.264) video codec and AAC sound.
RealPlayer, Apple QuicTime Player MPLayer VLC Media Player
SWF (Small Web Format/ShockWave Format) is a digital Adobe flash file format that stores vector-based animations, audios, and videos. Generally, it is used to stream media online, mostly browser-based games. Sadly, Adobe recently announced that they are ending Flash format support by the end of 2020 due to its shortcomings such as performance issues and lack of security.
Adobe Flash Player Adobe Flash Professional CC GOM Player Adobe Dreamweaver 2020