Both of those definitions have been somewhat fluid throughout time due to the change in context. I would argue that Collectivist Anarchism is a school of though with a well known origin and supporters. More of an academic endeavor (although experiments were made) than Anarcho-Syndicalism whose nature rooted in direct action make it more of a militant movement.
Collectivist Anarchism represents a specific school of thought founded by Mikhail Bakunin (1814-1876).
Bakunin's socialism was known as "collectivist anarchism", where
"socially: it seeks the confirmation of political equality by economic
equality. This is not the removal of natural individual differences,
but equality in the social rights of every individual from birth; in
particular, equal means of subsistence, support, education, and
opportunity for every child, boy or girl, until maturity, and equal
resources and facilities in adulthood to create his own well-being by
his own labor."
Collectivist anarchism advocates the abolition of both the state and
private ownership of the means of production. It instead envisions the
means of production being owned collectively and controlled and
managed by the producers themselves. For the collectivization of the
means of production, it was originally envisaged that workers will
revolt and forcibly collectivize the means of production. Once
collectivization takes place, money would be abolished to be replaced
with labour notes and workers' salaries would be determined in
democratic organizations based on job difficulty and the amount of
time they contributed to production. These salaries would be used to
purchase goods in a communal market.
It's important to notice that Bakunin Collectivism was proposed at a time when major schools of thought for Socialism (i.e. social ownership of the means of production) appeared. Bakunin was one of the most well known critiques of Marxism (see 1st International for more on this).
Anarcho-Syndicalism on the other hand has a more fuzzy origin strongly associated with notion of syndicalism. As Rudolph Rocker put it:
Anarcho-syndicalists believe that workers' organisations that oppose
the wage system will eventually form the basis of a new society and
should be self-managing. They should not have bosses or "business
agents"; rather, the workers alone should decide on that which affects
To this day Anarcho-Syndicalism is still very much associated with labour associations, notably the spanish CNT-AIT.
I always feel a bit hesitant when comparing two philosophies separated by time, context, and place, because a very objective, listed point by point, difference chart tends to lead to the conclusion that both terms are definite, strict things. They are not. You ask two persons, you get two answers. And I doubt you'll ever find written on stone rules for something like Anarcho-Syndicalism (for more refer to this source).
Syndicalism, like communism, collectivism, and mutualism, is one of the major trends for Social Anarchism. They mostly have different strategies with very similar objectives.
Anarcho-syndicalists, like other syndicalists, want to create an
industrial union movement based on anarchist ideas. Therefore they
advocate decentralised, federated unions that use direct action to get
reforms under capitalism until they are strong enough to overthrow it.
In many ways anarcho-syndicalism can be considered as a new version of
collectivist-anarchism, which also stressed the importance of
anarchists working within the labour movement and creating unions
which prefigure the future free society.
However, unlike other major trends, it does not have philosophers who founded its principles. It is instead a product of the context of the time:
Syndicalism is somewhat different, as it was far more the product of
workers' in struggle than the work of a "famous" name (although this
does not stop academics calling George Sorel the father of
syndicalism, even though he wrote about a syndicalist movement that
So it is actually possible that people identifying themselves as Anarcho-Syndicalists actually be practicing one of the other three (or others) schools of thought.