I think this is a very good question, but it is also a difficult question.

My experience up to now is that Korean and Japanese people have many things in common. Both peoples like rituals and formal language. I would say that Koreans are a little bit easier to get into contact with, Japanese are sometimes more shy and do not open up easily.

But beware, all this are generalizations which need to be verified in the actual case. Also, because of the difficult common past, both Japanese and Korean might react angrily when asked this question. That is really sad, I think.

For me, I am trying to get into contact with Japanese, Koreans and Chinese and the number relation is like 1 : 1 : 50 !! :)

I lived and worked there in Seoul, and have travelled in Japan.  Working in Seoul I found the Korean people simply do not like to speak to you at all unless you have been introduced - partly for shyness about English, and secondly for socio-cultural reasons.  The only people I got to befriend in Korea were ... Chinese workers! :D

Actually that's pretty similar in Japan too, exceedingly polite, but unwilling to speak and even so afraid they would run away (as in taxi drivers even when I had a map!)  But the difference I found was that Japanese would be shy but willing to try to help; in Seoul I found people would refuse to show they even saw me.

Hi, I'm a Japanese female who has been to Korea more than 20 times for fun.  And I also have an experience working with Korean at the travel company years ago.

What the big difference I felt with Korean were;

They respect their seniors at any scenes, especially about their parents, they do more than we do.   Korean students usually study more and harder than Japanese do.  That's why they speak English much better than us, even we may have the same kind of tongue and grammar problems when English learning.  (About tongue problem,  I've  heard that Korean language has much more vowels than Japanese , that would help them to be a good speaker.)  Also,  they are good at saying their opinions without any hesitations, that's why they  have a better presentation to make Westerners understand at work and school.

Today, it's said that one out of four Japanese learner is a Korean.  Because learning Japanese is pretty easy for them, and they want to gain any skills for their succeeding in their high competing working society.   But how about us? We study Korean just for our favorite K-pop stars!   Some Japanese people learn it for their work though.  Luckily or what, Japanese boys don't need to be in the services, so anyone has more choices to live and being in frank.

About our past, we Japanese still have to reserve.   However, today, we welcome any Korean and treat well. The guide books often tell us not to speak Japanese loudly when in public in Korea.  Because some elders remember the past and feel wrong.   Among our post-war ages, we have been getting good friends and enjoy sharing our culture and many other things but considering Korean's feeling.  (Honestly I'm interested in what about Japan they are/were learning at school.)

I have friends from japan and korea and some of them are my close friends, 

I could say that they have lots of differences in their physical appearance, you can identify those in their eye and eyelids, and sometimes the teeth structure. 
Japanese arent really much focused on the face but more on the fashion where in koreans, are so conscious with their face and their weight.
My korean best friend would always bring with her a mirror and checks it every know and then, goes to the bathroom and make-up check, I have many korean friends who had undergone plastic surgery too, but a few of my many japanese friends did plastic surgery.
Uhmmm, and I totally agree that koreans are more focused on the status and education.

But as what the first person who posted his idea, its a difficult question to answer because it may cause commotion or misunderstanding and perhaps some comments would lead to either negative or positive feedback.  

o～(▔▽▔o～)www .... Japanese dont like wear sunglasses. Japanese girls are smaller.(just my thought).