The Differences of Sushi and Kimbap

Kimbap or gimbap (the Korean roll):

The only rule for kimbap or gimbap seems to be that it be some kind of rice wrapped in seaweed. The rice is usually steamed medium grain white rice, but it can also contain other types of rice like 'forbidden' black rice, brown rice, and even other grains. Sometimes short sticky rice is  used on its own or mixed with medium grain rice. The rice is usually flavored with salt and sesame oil. 

The fillings can really be anything. They are are usually cooked but (I believe) raw fish would be ok too, e.g. spicy tuna. It's whatever works and is available. For example Spam is a popular gimbap filling but it's not like Spam is a traditional Korean food; it just got introduced there during the Korean war and was adopted into the cuisine. Raw or pickled vegetables are often used like carrots and cucumbers. And, sometimes a gimbap has no filling at all, just rice.

Finally the seaweed itself is usually toasted and/or flavored with oil (usually sesame, although other oils are used too), but it can also be plain and toasted, or not toasted at all.

Kimbap

(Note I'm not an expert on Korean cooking so hopefully someone will correct me if I'm wrong here) 



Makizushi (the Japanese roll):

The one rule for sushi rolls or makizushi is that the rice itself is flavored with sushi-zu or sushi vinegar: rice vinegar, salt and sugar. The term sushi itself refers to this vinegar-flavored rice*. If the rice is not flavored with that vinegar mix, it's not considered to be sushi even if it's wrapped up in nori. In Japan at least, medium grain white rice is the norm and other grains are barely ever used, not even brown rice. The rice is also cooked either with dashi stock or with a piece of umami-rich konbu seaweed in the cooking water.

Not all makizushi have a raw fish filling. Actually, the only raw fish commonly used as a makizushi rilling are various cuts of tuna and hamachi (yellowtail). Other fillings include raw or pickled vegetables (e.g. cucumber, pickled carrots, ), cooked food like tamagoyaki (sweet omelette) and stewed dried gourd strips (kanpyou), even canned tuna and mayo or  cheese and ham. I have never seen an unfilled makizushi though.

The wrapping is usually nori seaweed, which is toasted by never flavored, It can can be other things too like soy sheets, very thin omelette (usuyaki tamago), or 'inside-out' as with the California roll. 

Sushi

*There is a variation on the makizushi made with soba noodles called sobazushi, an exception to the rule.





Sources: Quora.com - Asian Cuisine