Question on Paris-CDG Immigration/Security for Self-Connecting Flights

4) people often confuse immigration and customs or assume they are the same thing. Immigration control (aka passport control) is where they check your passport and other information to see whether you are legally allowed to enter the country. Not every person who shows up with a passport is allowed in without prior permission. Customs is a check on whether your are bringing things like food, commercial goods, or drugs that are restricted into their country. So customs happens after you are allowed entry, and you have collected your baggage. Most travelers don't have customs issues. If you are connecting in the Schengen zone, these two things may happen at different locations - immigration at first stop, customs at final destination.

There can also be security checks in airports, coming and going, where you are asked to show your passport and/or tickets to make sure you're not potential trouble.

Carry-on luggage and a back pack for easyJet? You clearly have read their website instructions but I want to emphasize that they enforce their restrictions on what can go on board. It depends on the level of ticket. You have two bags; even a shoulder purse counts as one bag. And if you have to pay a supplement it will be much higher at the gate than in advance.
As to arrival, usually customs is a matter of simply walking through the green exit with the Nothing to Declare sign. But there can be spot-check inspections of what you are carrying.

already checked in online for my easyJet flight and got my boarding passes (on phone and printed out) and I will only be bringing carry-on luggage and a backpack so I'm not checking in anything.

You did buy the upgrade to bring that much carry-on baggage, right?

https://www.easyjet.com/en/help/baggage/cabin-bag-and-hold-luggage

CDG terminal info--- https://easycdg.com/airport-guide/travel-between-terminals-move-around-paris-cdg-airport/

@Southam and @joe32F

Yup! I bought an up-front seat for easyJet so it says on my boarding pass "You can bring on board ONE small cabin bag, which must
fit under the seat in front of you. Max 45 x 36 x 20cm (including any handles or wheels). You can also bring on board ONE large cabin bag, which must fit in the overhead locker. Max 56 x 45 x 25cm (including any handles or wheels)."

I saw that the https://easycdg.com/passenger-information/transit-connecting-flight-connections-paris-cdg-airport/ website says I can just follow the yellow transfer signs since I already checked in, but the https://www.parisaeroport.fr/en/passengers/flights/connecting-flights website says for self-connecting transfer: "Go to the baggage reclaim area by following the "Baggage drop" symbol (or directly to the exit, if you do not have any checked luggage). You will then need to check in before going to the gate for your next flight." But I already have checked in so do I need to exit??

I think the Paris Aéroport site is assuming you have checked baggage and/or have to get the boarding pass for your second flight at the main check-in desks, both of which are reasonable assumptions in lots of cases, especially if the second flight is a long intercontinental flight.

Of course, it's not always the case as is the case with you, but I think they are also trying to present what is the reasonable "worst case" (i.e. in the sense of most checks to go through) scenario for people making self-connecting transfers.

Would love to hear what you ended up finding out... I have a very similar situation in a few weeks with slightly less time so would love to know if we don't have to exit the airport and can just go straight to our gate.

You will not have to deal with immigration or customs at at CDG. You will go through immigration/passport control at KEF. You have no checked luggage so you will not even walk past the customs area which would be walk through anyway unless you had something to declare.
Edit: I saw after answering that this is a revived thread. I am leaving my answer in case it helps any future questioners.

At CDG, you just stay airside while changing terminals, as JHK said, but go through security as you enter your new terminal.

Hi @jordandinsmore

When I landed in KEF (Iceland) from the US, I got off the plane and went up to a passport control booth (no wait at 6:30 AM). The lady just asked where I was going and when I was coming back and got my passport stamped. I probably only went around the airport for 20 minutes (I only used bathroom and got juice) before lining up to board for my flight to Paris. When I landed in Paris, I didn’t have to go through customs or security or anything (didn’t have to do a form on the plane either). Since my next flight (I bought ticket separately) departed from the same terminal, I didn’t have to go through anything else. But if you have to change terminals, there’s these gates that you probably either do a quick passport control check or security with a person. The gate was very narrow (looked like you just walked through some metal fence/turnstile?) so I doubt it takes any more than a few minutes. Also I landed at 1:10 PM in France in case that helps with timing! My 2 hour layover was plenty of time for self connecting flights in the same terminal with only carry on luggage/backpacks. I had time to eat as well.

Thank you all, appreciate the information. We were starting to get a little worried while doing some research but sounds like we should be fine.