All Wiccans are neopagans. Most neopagans are not Wiccans. Most pagans are not neopagans.
There is a misconception among many that Wiccans, pagans, and neopagans are all the same people. In fact, they are subsets of one another.
What is a Pagan?
Pagan has been used by Christians to describe unbelievers for many centuries. Today, we generally use it to refer to those of non-Abrahamic faiths. That is to say, Hindus and ancient Greeks are both pagan, but Muslims and Jews are not.
The thing is, many pagans do not use the word to describe themselves. Pagan describes what a person is not (Christian), rather than what they are. Hindus want to be known as Hindus, not as pagans, which they consider derogatory.
What is a Neopagan?
There are, however, a group of people who do identify themselves as pagans, and this is people who belong to the modern pagan movement. These are modern religions which are influenced by older pagan religions. To differentiate them from the vast sea of other religions often described as pagan, many of us label them neopagans, the new pagans.
Wicca is one of many neopagan religions. In fact, it is one of the oldest. But “oldest” still means only about 80 years old.
Some neopagans religions are reconstructionist religions, which means they are attempting to reconstruct pagan religions that have died out. The best known of the reconstructionist religions is Asatru, often called heathenry. Believers study Norse culture and mythology, practicing their faith as accurately as possible within legal and certain social boundaries.
Other neopagans are eclectic, such as Wicca. They borrow from a variety of different sources and forge it into something new.
So most religions on the planet are pagan, and neopagans are a small subset of that group, and Wicca is just one of many neopagan religions.