The short answer:
A country can have different official flags for different purposes. A civil flag, state flag, naval ensign and royal standard may all have different designs.
A country can have different official flags for different purposes. A civil flag, state flag, naval ensign and royal standard may all have different designs.
Civil flags
A civil flag is generally intended for use by citizens and civilian organisations. Some countries distinguish it from a state flag used by government institutions.
State flags
A state flag may include a coat of arms or other emblem that identifies the government or state authority.
Naval flags and ensigns
Ships often use specialised flags known as naval ensigns. Their designs can differ from the ordinary national flag.
Royal and presidential standards
Countries with monarchies may have royal standards, while some republics use presidential standards. These identify a particular office rather than the country as a whole.
Why the distinction matters
When you see a flag that looks slightly different from a country's familiar national flag, it may be a different official version rather than a mistake.