sym() creates a symbol from a string and syms() creates a list of symbols from a character vector.
expr() and quo() quote one expression. quo() wraps the quoted expression in a quosure.
The plural variants rlang::exprs() and quos() return a list of quoted expressions or quosures.
enexpr() and enquo() capture the expression supplied as argument by the user of the current function (enquo() wraps this expression in a quosure).
enexprs() and enquos() capture multiple expressions supplied as arguments, including ....
exprs() is not exported by dplyr to avoid conflicts with Biobase::exprs(). Use rlang::exprs() even if you have attached dplyr.