Symbols - What does heaven look like
A seraph and also a seraphim are Intelligences. The names are simply synonyms brought in by the Christian church to provide alternative names for the Planets [and lower levels of Intelligence].
Please see Intelligences and their synonyms for a table which shows all the Intelligences and the many synonyms that exists. Seraphs are any level below the top level of Seraphim. In art they have become personified, often very beautifully, with wings and a host of other symbolic additions. Those who 'see' Seraphs in visions or hallucinations do not see anything like the images in art. All that is apparent is the power - Light and Power.
Seraphim - painting by Masaaki Sasamoto
For iPad/iPhone users: tap letter twice to get list of items.