same style giving different results!

• Did you apply a character style in one or both documents.
• Are the styles based on different parent styles?
• Use both document the same fonts of the same manufacturer?

There is no video attached? Or maybe it is still uploading?

Anyway, if you are talking about copying thext to another document - and you get different formatting - then it's because there is a different formatting in:

a) style definition itself - when you copy text, InDesign is using name of the applied Char/Para/etc Style(s) - do not copy original formatting - so if the same name already exists in the destination document - then formatting of this style is used,

b) there is a different style definition in the "BasedOn" style.