experienced:
ignorant,
inept,
immature,
incompetent,
unsophisticated,
green,
untrained,
unskillful,
untalented,
unskilled,
inexperienced,
unable,
unfamiliar,
unseasoned,
incapable,
unknowledgeable, amateur.
professional:
stupid,
unintelligent,
unprofessional,
clumsy,
inefficient,
rookie.