I`ve always considered the forward to be a more creative type player - perhaps one who can drop off - who is more likely to lay on chances for others while not quite having that killer instinct (e.g. Van Persie or Wayne Rooney). Whilst the striker is your "fox in the box" the one who doesn`t always do a job for the team but just seems to sniff out goals (e.g. Michael Owen)
Of course this isn`t a generalisation and doesn`t fit all the time. The explosive striker seems to be a subset, they create chances through sheer pace and turns.
Anyway, I have always try to combine a forward and a striker as a front pairing - again this doesn`t mean I haven`t had good dual striker pairings but they never seemed to click as a pairing and were more reliant on the midfield playing the ball to them.