I wanted to do a comparison of some interesting birds but, with cool outdoor temperatures still (and limited access to parks due to the current COVID-19 lockdown), I used a postcard someone had sent me years ago showing six different owl heads. I chose two that I have personally seen and sketched them below, then looked in my bird guides for information on each one.
1) I learned there are many differences in colour, size, shape, and behaviour between the two species although they have common features, such as no ear tufts and large facial disks to gather light while hunting at night.
2) I think it's possible to combine drawings, written comments, and measurements or other numeriacal data on the journal page as they come to you (or as you find things in research material). This somewhat cluttered look appeals to me as it makes you study the finished page more carefully later when you want to review all the facts and features of the observations.