Is Anglophone interchangeable with English speaker?

I found the following answer to the question asking “Language understandable to English speaker without learning” posted in EL&U site:

“Conversational German would be somewhat accessible to a native English speaker, but aside from conversational pleasantries afforded us all by UG, most Anglophones do not understand German.”

I’m curious to know whether there is a significant difference of meaning and nuance between English speakers and Anglophones.

OED simply defines ‘Anglophone’ as an English-speaking person, while CED defines it as a person who speaks English, especially in countries where other languages are also spoken,-e.g. Kenya and Zimbabwe, and Merriam-Webster defines it as the adjective and noun - consisting of or belonging to an English-speaking population especially in a country where two or more languages are spoken.

What is the exact definition of Anglophone? Does it mean only English speaking people of the countries that once were ruled or under the influence of the British Empire including India, Hongkong, Singapore and South Africa?

Are English speaking Belgian, French, Dutch, German, Swiss of the countries where other languages are also spoken Anglophone? How about Japanese, Chinese, or Korean English speakers?

Is there word, native Anglophone as well as native English speaker?

I agree with @Bill's comment - to me, Anglophones are normally native speakers only.

But for me, that's largely because I wouldn't normally refer to "an Anglophone" in the first place. I use the plural form specifically to include people from many different countries who speak English as their mother tongue. Anglophones are representatives of whole linguistic communities.

But by most dictionary definitions, many non-native speakers here on ELU qualify as Anglophones (they speak English), so I can't deny that technically speaking Reg Dwight, for example, is an Anglophone. But in most contexts where I want to convey that someone speaks/understands English [fluently], that's how I phrase it. I've no real use for a word meaning person who speaks English fluently - either by birth, or through extensive exposure/familiarisation later in life.

For most people (read, me), Anglophone either identifies those specific members of a multi-lingual population having English as their primary language, or it collectively identifies all native speakers. But you can't normally "learn" your way into either category; you have to be born into it.

The direct answer to your titular question is that yes, anglophone is in the general case interchangeable with an English speaker. The OED says that an anglophone simply means “an English-speaking person”, and that as an adjective, it just means English-speaking. All other nuance beyond that is going to vary from person to person, and you are unlikely to find perfect agreement on it.

For some, the term anglophone also implies a certain culture. This is probably because an anglophone country is one whose primary language is English—which, outside the British Isles, usually means one originally colonized by England when she was an imperial power. Britain, Ireland, America, Canada, Australia, and New Zealand are all anglophone countries, and perhaps several others.

The OED also notes that the word is often seen with a capital letter, although its primary entry lists it without one, perhaps to better match francophone, hispanophone, lusophone, and the like. Note that a sousaphone is something else again. :)

As an African myself i know that countries in Africa where English is the official language are usually refered to as Anglophone countries whilst native English speakers are people from Britain and the USA.

In Canada, anglophone is commonly used in areas where French is spoken to refer to the English-speaking population. Similarly, francophone is used in English-speaking areas to refer to the French-speaking population. Francophone is also used in French-speaking areas to refer to French speakers.

However, you won’t commonly hear an English speaker referred to as an anglophone in parts of Canada where there isn’t a significant French-speaking population. So anglophone isn't always interchangeable with English speaker here.

Anglophone refers to any English speaker, regardless of country of origin or heritage. In Québec (the main French-speaking area of Canada) a person whose mother tongue is something other than English or French is called an allophone.