Teleportation is point to point travel and NEARLY instantaneous. Disappearing from one point and reappearing in another point. However you normally need to know the location you're going to by having already been there, or having a really good idea where through visualization and detailed explanation. Like you can't just teleport to something you've been told if all you have to go by is a coordinates unless your character knows every coordinates of existence.
There are ways around this however, like if you say- sense something in the point you need to teleport to. Using that as a guide you can teleport but would not know the location until you're there. Once there, it becomes a place you can teleport to. You cannot unknowingly teleport to just somewhere random. Like "So and so teleported without a destination," this would not work and would not even be considered a botched teleportation as the spell or even technology would not know where to go and you'd just remain there. Which for a good example is why K2 had to use a dimensional PORTAL though we call it teleportation to originally get to the Mortal Dimension years back.
PORTALS on the other hand are as people have explained, doors; Rips through the very fabric of existence and dimensions whether clean, a physical door or completely ripped. In magic portals you DO NOT always need to know your location. You can create a portal to any random coordinates or location just by thinking it. Of course it can still work through visualization if you DO want to know your location. However you don't need to have already been there, sensed something as a lead, or need enough information about the location in general.
Portals also use less energy depending on the distance and are less instantaneous than Teleportation. Also, where Teleportation cannot be blocked unless in an AT field (magic or tech), portals can be blocked by raising other portals, spells, or other such effects that are more than just an AP field. Simply by closing the door as well. If tried on Teleportation, the effect is too instantaneous to be affected.
BOTH can be botched, however if a portal is botched, you're just stuck where you are parts of you in both places as there is no 'in between' you have to go through. If a teleportation is bothced and the split second in-between is botched, you get pulled to Deletrius the land of the lost. Also, barriers can stop portals due to the area of effect, but they cannot stop teleportation unless laced with the counter spell against it.
ALSO another thing. If you want to teleport more than just yourself to include say, a group, another person, or even a planet. You require more energy, focus, and concentration and it becomes a 'mass teleportation.' Depending on the distance can also use more energy and exhaust you. Like if it was a dimensional one.
BUT if you use a portal, it's just a contact and more than one person can go through at a time depending upon size, with distance not being a factor in how much energy you expend. Less exhaustion on the mage. Portals will also remain open until you close them.
