Cabala is Fulcanelli's term for a special use of language, drawing on phonetic similarities and other symbolic techniques for expanding the expressive reach of words. This is related to the Green Language or Language of the Birds of the alchemists.
Kabbalah is the Hebrew body of mystical tradition which contains techniques such as gematria, notariqon and temura, drawing on numeric equivalences of letters, numerology, permutations of letters, forming new texts by picking first letters of words and other such text manipulation. The Tree of Life and its sefirath are also part of this tradition. Kabbalah is most often applied to the Hebrew text of the Torah.
After a fashion, both are techniques for deriving additional meaning from text. However, practicing each draws on a radically different faculty of the mind. Kabbalah is mechanical and rigidly formal, whereas cabala is unpredictable, creative, rich in texture of symbolic meaning.
In Gurdjieff's terminology, kabbalah can be practiced by the formatory apparatus, whereas cabala requires the interplay of abstract thought and visual, auditory and emotional functions.
Fulcanelli writes that phonetic cabala is the key to understanding alchemical texts and symbols. Cabala combined with study of word roots configures the mind so as to have a richer set of associations to draw from and expands the semantic space open for contemplation.
Ultimately, this expansion of the faculty of language can reverse the 'babel' effect of confusion of tongues by connecting to a level of thought from which individual languages are only partial projections.
In contrast with this, kabbalah occupies one with tedious calculations which can just as easily be performed by computer. This has indeed been done, with the result of finding all kinds of 'hidden content' from the Bible, as well as from any other large body of text. The findings seem to be artifacts of probability and involve no particular conscious work. From a nearly forgotten practice, kabbalah rose in the 12-13th centuries to a prominent status in Western esoteric circles. Laura Knight-Jadczyk suggests that this may have been a deliberate maneuver to send centuries worth of seekers chasing their tails.
See Secret History, Fulcanelli
The practice of cabala can disclose meaning in alchemical text, but what may be even more important, it is an exercise which is its own reward, as it generally enhances one's language abilities and enriches one's semantic space. This is a part of connecting the human mind to the Platonic plane of ideas.
The notion of semantic continuum is discussed in the Grail and Adventures series at the Cassiopaea web site. Fulcanelli's books are prime examples of multilayered language and cabala.
See Green Language, Language of the Birds, Alchemical Terminology.