The orbital letters are associated with the angular momentum quantum number, which is assigned an integer value from 0 to 3. s correlates to 0, p = 1, d = 2, and f = 3.The angular momentum quantum number can be used to give the shapes of the electronic orbitals. s orbitals are spherical; p orbitals are polar. It may be simpler to think of these two letters in terms of orbital shapes (d and f aren't described as readily).
The electron configuration of an atom denotes the distribution of electrons among available shells. The standard notation lists the subshell symbols, one after another. The number of electrons contained in each subshell is stated explicitly. For example, the electron configuration of beryllium, with an atomic (and electron) number of 4, is 1s22s2 or [He]2s2.