What is different about tretinoin and retinal?

Mainly because of the axial of the earth. When it is summer in the northern hemisphere it is winter in the southern.

Different can be a lot or not much. A lot could be a total opposite of something that has happened before or is happening now.

Some restaurants change their menus according to lunch or dinner. Some have the same menu all day. Some are only open for one meal. It depends.

its different because in different countries ppl have different styles and plus they speak different languages. Also another reason is because there is always going to be something different...

Yes, different dreamcatchers have different meanings.The symbols have short spells on them to keep bad dreams away.then some tell a story about long ago.The rest have spells that help good dreams...