Self-seeking is listed as a synonym for selfish. Selfish is listed as a synonym for self-seeking. The other synonyms listed for the two words overlap in so many ways it is beyond the scope of defining words in an objective way to tell them apart. For our purposes, we choose to look at two different parts of the same thing inside us by considering them separately.
self·ish
adjective: selfish
(of a person, action, or motive) lacking consideration for others; concerned chiefly with one's own personal profit or pleasure.
self-seek·ing
adjective
having concern for one's own welfare and interests before those of others; self-serving.
SYNONYMS FOR self-seeking
boasting
bragging
egocentric
intimate
obsessive
personal
superior
affected
aloof
autocratic
boastful
conceited
egoistic
egoistical
egomaniacal
egotistical
haughty
individualistic
inflated
inner-directed
intrinsic
introverted
isolated
narcissistic
opinionated
pompous
prideful
proud
puffed up
self-absorbed
self-admiring
self-centered
self-important
self-involved
self-serving
selfish
snobbish
stuck on oneself
stuck-up
subjective
swollen
vain
vainglorious
wrapped up in oneself
SYNONYMS FOR selfish
egotistical
greedy
narcissistic
self-centered
egocentric
egoistic
egoistical
egomaniacal
egotistic
hoggish
mean
mercenary
miserly
narrow
narrow-minded
out for number one
parsimonious
prejudiced
self-indulgent
self-interested
self-seeking
stingy
ungenerous
wrapped up in oneself