Okay Cardigans compared to Pembrokes in personality:
Similar, but night and day and keep in mind these are in broad generalities. I know Pembrokes which fit more in the Cardigan description and Cardigans which fit more into the Pembroke descriptions.
Pembrokes are the 3 Stooges and Robin Williams rolled into one; Cardigans are the Marx Brothers.
Pembrokes believe the world is a party just for them; Cardigans wait for the invitation to a great party.
Cardigans look before they leap; Pembrokes run off a cliff and then figure a way to get out of it.
Pembrokes will run with scissors; Cardigans don't.
I wouldn't say that marking after getting excited about a perceived insult from a passing dog is a true trait of Pembroke males, I know Cardigan males that might do the same, especially intact ones; but don't see that much in either breed really.
Pembrokes rarely meet a stranger - they're just friends they haven't met yet and might go home with anyone who has the treats; Cardigans tend to wait to be introduced before they have a new friend and will accept "candy from a stranger" usually after owners give an okay; but they're going home with "mom or dad."
Both breeds can be territorial, but I believe what Cardiguy is seeing in Ruby is the owner loyality that shows a little more in Cardis, than in Pems.
I'd trust my well being and safety more with my Cardigans than with most of my Pems. IF my Pems react negatively to someone, then I really take that as a serious character assessment.
Personality and temperaments can even be related to structural differences -
Pembrokes have a little "sharper edge - their ears are "triangular" and their bone is oval. Cardigans have "oval" ears and their bone is round. (Or supposed to be.) Pems come from a Spitz background, Cardis from a Teckel or hound (Doxie/Bassett) background and it shows in their looks and personalities and barks.
I saw a good example of the differences between the two breeds today at a corgi gathering today. There was a puppy of each breed inside a fence watching people milling and cleaning up. Neither one of them was missing a trick or a movement. The Pembroke was up on all fours, standing alert and at attention watching so as to not miss a thing. The Cardigan was lying on its tummy, nose pressed up against the fence exposing its teeth as if making a face and just taking all the activity in. A Cardi and a Pem can be doing the same activity, there will just be a different nuance to the way they do it.
IF you want more, I'll keep going.
Debbie