Portals are (simply put) a location where a wide variety of unexplained phenomena occurs in a defined geographic area.
Famous supposed portals have included places like Bennington Triangle, Skinwalker Ranch, and Bridgewater Triangle. As well, the San Luis Valley of Colorado is well known for being a gateway for weird unexplained events and creatures. These things include odd weather events, UFOs, ghosts, spook lights, cattle mutilations, Bigfoot, prarie dragons (supposed translucent lizards of a sort), ghostly cowboys, a blue lady, ghostly Native Americans, and flying humanoids.
One citizen decided to build a UFO tower outside of the town of Hooper where people come from all over to see the strange disks, cigar shaped vehicles, and weird lights. The land owners says there is a portal on the land. Visitors are encouraged to leave trinkets in the vortex garden.
What is the purpose of a portal? It's commonly believed to be an entry/exit site from this world to another, more than likely another dimension or parallel universe.
Some people use vortexes and portals interchangeably. A vortex is the convergence of leylines (earth energy lines) that creates a powerful psychic energy. Glastonbury, England is considered a powerful one and many historic ancient monuments were interestingly built upon them. Sedona Arizona is said to have four energy vortexes.
The difference would be that a portal reports a great deal of odd unexplained and sometimes frightening phenomena and a vortex creates a spiritual energy that is uplifting and inspiring. One might go to Stonehenge to feel the power of a vortex, but run away from San Luis Valley when they see a UFO in the sky doing strange maneuvers.
Bennington Triangle in Southwestern Vermont.
Bridgewater Triangle in Southeastern Massachusetts
San Luis Valley, Colorado
Panther Meadows, Mount Shasta
The one commonality in both vortexes and portals is that they involved a philosophy that is earth-based and that the earth is somehow creating the right conditions for both energy vortexes (swirling concentration of energy) and portals (entry/exit sites to other worlds). Given that we live on a planet with an extraordinary capability to create a huge diversity of life that is interdependent, such phenomena seems like small potatoes for such a generator of power, climate phenomena, tides, gravity and more.