The main difference is the introduction of qsql (SQL-ish statements can be treated as expressions) and some utility functions that are defined in K. QSQL is mostly for business analyst folks, and is just syntax sugar over the K-native `?` and `!` functions (which is more powerful than qsql).

Q is K syntactic sugar to make the system easier and more "traditional".

q is k with all of the monadic verbs being replaced by English words: `+` is `flip`, `=` is `group`, `-` is `neg`, and so on. It also has q-sql, a SQL like sublanguage for conveniently working with tables. k has the verbs that implement it, but they're not really as convenient.