While Lisbon is the Capital of Portugal, and considered the most important city in the country, Porto is known as the second-most important city, and the “northern capital”.
Lisbon airport has about 3 times more passengers landing, than Porto Airport (in 2019, about 30M vs 10M in Porto).
The distance from Lisbon to Porto is about 310km (185mi), and the driving time about 2h45 (one way), or 5h30 (roundtrip).
There are two major highways connecting both cities (A1 and A8). While A1 is the most popular one, going through famous cities such as Fatima or Coimbra, the A8 goes along the coast, going through some villages such as Obidos, Nazare or Aveiro.
The best-recommended way to travel from Lisbon to Porto is using a private car transfer service.
This has a cost of 198EUR Per Person (direct transfer), with reservation here: https://portugal-magik.com/tour/private-transfer-from-lisbon-to-porto-direct/
Or, alternatively, a private transfer service with 2h stops on the way, for 650EUR up to 4 guests, available here: https://portugal-magik.com/tour/private-transfer-from-lisbon-to-porto-with-2h-stop/
The other option would be renting a car. A medium-size car with full insurance from Europcar or Hertz, should cost 150EUR to 200EUR for one day. If you leave the car in a different city, an additional fee should apply. Then you should also consider gas, tolls and parking (about 80EUR for gas, roundtrip, about 50EUR for tolls, roundtrip, and then parking depending on where you park and for how long, but eventually 15-20EUR per day).
For any questions, drop me a message below.