The Celtic scholars today are used to collect all the ideas and ancient legends and from various successive cultures being installed in the territories said Gaul. There are fundamental differences between the two languages, same as in the styling works found a schism. The two cultures were mixed with varying depths depending on the location and the tribes, for sure, but many Gallic tribes ample evidence that this is not a post presence in the Celtic settlements. It is impossible that civilization is influx from the outside without that we have found traces evidence. So the Celts arrived after the installation of the Gallic tribes. Regarding the awarding of legends and myths, I do not think that the Gallic tribes fraternal completely copied their culture with that of arrivals. There are more significant differences in religions practiced sacrifices and worship of the dead. These two civilizations are mixed but not a complete osmosis. The Celts are installed rather to the northwest of Europe, England, Scotland and Ireland, the successors Gauls kept their territories west-central Europe, settling even until today Turkey. Gallic existed until the sixth century AD, must not forget the Celtic cultures which are already the most erased First Century.
In fact through the mythological study, it is apparent that the Gauls and the northern tribes have a common past at least as important as with the Celts and Greeks.
Another important fact is the difference in eloquence, the Gauls are famous for their verve and asides, not Celtic.
Another thing, the Gallic language is not a Celtic language, some words are common but Greece, Egypt and the Iberians also brought their lots lingual creations. The most significant difference being the fact that the Celts for human corpses rotting their doors while the Gallic Druids mingled with Greek Phylosophycal.