In brief and to over-generalize, "persona" and "impression" are Hobby jargon, and not universally agreed upon terms. As I use them...
A "persona" is a more detailed "impression" that is interpreted and portrayed in the "First Person" as well as in the specific Everyday Life and Experience details of a person.
An "impression" is more generic, universal, representative than a person, and is portrayed in the "Third Person."
"Personae" are a Sliding Scale of detailed information about either real people or made-up people that deals with who the person was- where he/she was born, to whom, what family members, what upbringing, education, occupation, religion, politics, beliefs, hopes, dreams, Life experiences,likes, dislikes, druthers- combined with what the person looked like physically, how they dressed, spoke, etc., combined with what they did or do.
"Impressions" of the "Third Person" type are a Sliding Scale of visual information or presentation such as what a Civil War soldier or civilian wore, carried, used, and did in a "Civil War soldiers marched and drilled." Or "They ate hardtack."
In some, many ways... it is very hard to know "everything" about the "mental and physical" man ( or woman) so "personae" often tend to be the best researched "composite" we are capable of putting together as it is rare to impossible to know the fantastic detail that is/was a complex, breathing human being living in his/er Time and Place.
And as they say... the rest lies in the "details."
Others' mileage will vary...
In gleichem Schritt und Tritt, Curt Schmidt
Not a real Civil War reenactor, I only portray one on boards and fora.
I do not portray a Civil War soldier, I merely interpret one.