Difference between journals and diaries:-

The difference between a diary and a journal is that a diary is where you can write down what happened during the day and keep a record of stuff. A journal is to write your own personal feelings in, and things that happened, and how they happened.
A diary is a report of what happened during the day—where you ate, who you met, the details that what was happened in the office, and who took whose side. It is a like a newspaper about you.
A journal is completely different. A journal is about examining your life. It’s a GPS system for your spirit. Journals lead to insight, growth, and sometimes, achieving a goal.
You can keep a journal in anything that feels comfortable and that’s portable–a spiral notebook, a bind book you have put together with lokta paper, index cards held together with a rubber band. You can use a computer; keep a blog, although that doesn’t work as well for me. But things on the internet are simply not private, password protected or not.
To keep a journal on paper, pick a time of day to write. Keep it regularly. It makes it easier. Try that you didn’t stuck to an exercise program because then it can nailed it into schedule at a certain time. Writing works the same way. First thing in the morning, last thing at night, while eating lunch at your desk. Write with a good pen that feels good and whose color you like.
In the beginning, you may have to set a time limit. Three minutes is good. Just write whatever comes into your head. No editing, no crossing out, no reading it in your mind in front of the committee who lives in your head and judges your writing.
Journal prompts are ideas or thoughts to get you started writing. They help you focus on a topic. You can use one over and over for a week, to see your different answers, or you can use a different one every day.
In simple words diary is where you write daily about what you did and a journal is where you write whenever you feel like it. Journals can contain poems, drawingings, etc. Whatever it takes for you to get your feelings out on paper.
It doesn't really matter that much though. The thing that matters the most is whether or not you get what you're feeling out. In a journal or in a diary you can write whatever you are thinking/feeling with worrying about what others will think or if it will hurt someone else's feeling since both are for your eyes only unless you choose to show someone else.
A journal is more factual, less opinion, and pretty much what you did for the day. A diary on the other hand is more opinion, juicier, and contains things that you probably wouldn't want to reveal to anyone. Just like our personal thoughts.
A diary is strictly a record of personal and daily experiences. Journal could mean a more general record or logbook but more importantly a technical journal, that is a scientific or industry-related publication/periodic.
Sometimes it is sad that, "Girls keep diaries, boys keep journals." I think they both mean the same thing, but you normally wouldn't hear a boy say, "I'm going to write in my diary." They're more likely to say, "I keep a journal.
By all this we can also use a synonym for journal which can be ‘’Diary’’