From Minecraft Wiki
Portal may refer to:
Nether portal – the specific formation of obsidian blocks that create the structure used to travel to the Nether.
Nether Portal (block) – the purple, indestructible, transparent, vortex-animated block that fills in a nether portal.
End portal – the specific formation of 12 End Portal Frame blocks that create the structure used to travel to the End.
Exit portal – The exit portal from the End, framed in bedrock.
End gateway portal – The portal to the outer islands of the End, framed in bedrock.
End Gateway (block) – The black, indestructible, starry-animated block that fills in an end gateway portal.