how can the differences between french and american culture can affect
a french guy?
what are the differences between french and american culture?

I think one important difference is due to the fact that France didn't
go through the purging of Communists and Socialist that America went
through after WWII. France is thus a much more socialistic society
with strong unions and much stronger belief in the value of state
intervention in society.

Because of their revolution, France is much more of a secular society.
The French are much more likely to accept the notion that religion is
a personal matter and should play little to no part in public policy
and government institutions such as schools.

Other differences:

There is a latent resentment in French culture and civilization
because the are much less powerful and influential than they once
were. There is a collective memory of a time when France was a
pre-eminent power in the world. They were a challenge to British
power, they had colonies, their language was use all over the world
and waxing in influence and they were recognized as a great center of
culture. But this has since been lost, their power being eclipesed by
the British and then the Americans. Then to top it all off Hitler
kicked their a**es and rolled into Paris with all those tanks.

America on the other hand has a confident swagger about it. They got
rid of those pesky natives living on the land they wanted.
Industrialized, won wars, invented amazing things that have changed
the world, sent their people to the moon and defeated the Soviet
Union. They have watched their power and influence increase and spread
for more than 2 centuries now.

The French would say that the Americans have no culture.

About 10 years ago I went to a trade exhibition at Disneyland France
- it was for a sector of very well travelled, international freeloaders
- a totally dim venue

It was quite amusing, we 'exhibitionists' and the French staff found
that we had quite a lot in common - a total contempt for the venue.

Augusta's last post misses one other point, they got invaded by the
Germans in 1870 ( Siege of Paris and eating elephants ) they got
duffed up in 1914-18 and effectively occupied by British, Colonial and
American troops, then they got thoroughly invaded in 1939-45

As the Grandmother of that amusing author Florence King allegedly said
about the virgin birth: 'young women in occupied countries do get into
trouble'

A little genetic insecurity could make people touchy. :)

Personally I have nothing against the French, they have made great
strides since the 1960s when the water was dodgy and the electricity
was 120v DC (?)
- also their tube trains looked like relics of the 1880's
... and those squat bogs ... they were a problem

Regardless, now they look pretty affluent and organized, even if they
take eight weeks holiday a year and enjoy long lunches. If in need of
a little cultural 'shock and awe' they can always visit a medieval
town, mooch round a cathedral or admire a Roman aquaduct.

Their real clincher is the Statue of Liberty

The difference could be represented in the 'Statue of Liberty'.

The French have the history to create this beautiful piece of Art,
whilst the Americans, as a young nation, have the passion to worship
it.

France is one of the largest countries in Europe, and the US one of
the largest in the world. Both have widely differing regions; and both
are multicultural.  So when you refer to French culture, do you mean
the culture of the average Parisian or someone from rural Auvergne; of
a Catholic man whose family are French from way back, or a young
Muslim woman whose parents emigrated from N. Africa 30 years ago? By
American culture, are you thinking of the culture of a Jew from NY or
LA, of a fundamentalist Christian from the Mid West plains - or of an
African American, a Latino, or an immigrant from Vietnam (of even of
an indigenous North American Indian)? The point I'm making is that
there is no single French cultural identity or single American
culture; and the best way for any individual to approach a foreign
country and its inhabitants is with a tolerant, open mind, and with as
few preconceptions as possible.

I think that having accurate and flexible preconceptions is a good way
for any individual to take on new experiences including foreign
countries and their inhabitants.

It is helpful for people to have modifiable guidelines that they can
use to make beneficial decisions in new situations. So bring on the
preconceptions and then use real world experience to update and
improve them.

Americans may have preconcieved ideas that the French are rude and
that they do not bathe enough.  There is also some current residual
resentment about the French government's opposition to America's
invasion of Iraq.  We were even calling "French Fries" "Freedom Fries"
at one point.  Just FYI.  Good luck to you.