It probably because I watch them around the same time but I felt they had a very similar vibe. They were family friendly series to watch. Both are about problems the female leads goes through before falling in love with ML

Both are dealing with palace politics wanting more with each episode! The only difference is that Rise of Phoenixes has a bit more of a love story attached to it.

Both series revolve around a case that isn't solved and deal with palace politics. I felt on edge wanting to know what was going to happen with the next episodes. Both of them gave me the same excitement! The only difference that I spot right away was that The Longest Day in Chang'an had amazing cinematography and I love the coloring. Gotta admit it captived me on the first episode therefore I couldn't stop watching. I didn't know what was in store for me when I started both series.

The love between ML and FL reminds me of Akai Ito. Something holds back ML and because of that he doesn’t pursue FL right away.

Both series start out with an idol group that is no longer popular and no one really pays attention to anymore. I believe both FL are the leaders of the group, they struggle to make it in the entertainment world but as they meet headstrong ML, slowly ML starts to have feelings for FL.

FL disciple of ML
Both ML made decisions not to get married but that slowly changes over time because FL
One and Only just has a slow-burning love whereas in Pearl Eclipse I felt ML was a bit more aggressive.

Virtual world and Love, at least that was the start of the story!! Love crossed has a bit more complex storyline with a twist whereas Holo Love was just a common love storyline with the FL lead not being able to see faces but she can see ML.

Both FL gets a new identity as they plot for revenge for their family. Both FL comes from royal family taking on the identity of her maid or family friends identity.

With JJL series starting out automatically with her trying to survive with a fake identity it automatically remind me of Wei young.

The struggles youth goes through, but Go Ahead deals with a more complex family structure, Record of Youth is a bit more light-hearted.

It might be because I just finished both of them around the same time but I often thought their similarities how both are struggle of youth and it is heart warming.

If you like love stories that start after marriage, this is it for you! RB has more cuteness more chemistry between the leads.