Not really. In conventional usages, the term "dialect" is usually reserved for variations within the Standard English varieties of the various nation-states where English is the dominant tongue--e.g., American English, Australian English, Canadian English.
British English is not a single dialect.
There's no such thing as "American." American English is a dialect of English that is more has more than 95% lexical similarity to British English.
No, American English is pretty distinct from British English at this point, especially what most people think of as a Southern dialect. The closest dialect of American English to British English (I assume you mean BBC British, because British dialects get more disparate the farther down the social ladder they go) is probably something in New England very near the East Coast, or maybeupper-class coastal Southern English. The problem is that the accents have remained more similar than the dialects have.
While some Southern dialects share certain features with British English, such as the non-rhotic "r" pronunciation, they have evolved independently over time. Both American and British English have unique characteristics shaped by their own historical developments and cultural influences.
No, American English is pretty distinct from British English at this point, especially what most people think of as a Southern dialect. The closest dialect of American English to British English (I assume you mean BBC British, because British dialects get more disparate the farther down the social ladder they go) is probably something in New England very near the East Coast, or maybeupper-class coastal Southern English. The problem is that the accents have remained more similar than the dialects have.
No. American dialect is different from the British.
English (American Dialect)
It depends on the individual's familiarity and exposure to each dialect. Some may find American English easier due to its standardization and prevalence in media, while others may find British English easier due to its clearer pronunciation rules. Ultimately, both can be understood with practice and immersion.
In the American dialect of the English language "football" is one sport, "soccer" is another. In the British dialect of the English language, the sport the Americans call "soccer" is called "football" they do not play much American Football in Britain.
The most widely understood English dialect
Normal American English
Language-dialect would be nuances like a southern accent.