A hdmi splitter and a switch do opposite jobs, and the words get used interchangeably almost everywhere, which is why this is the easiest part in the range to order wrongly.
A splitter takes one source and sends the same picture to two or more screens — one laptop driving two monitors showing the same thing. A hdmi switch does the reverse: several sources into one screen, so a console, a streaming box and a laptop can share a single TV input.
Ask which side has more cables. More screens than sources means a hdmi splitter. More sources than screens means a switch. Powered units handle longer runs and higher resolutions more reliably than passive ones, and are worth the difference on anything above 1080p.
