The general principle is that mitosis creates somatic cells and
meiosis creates germ cells.
However, I cannot agree. Each gametogonium needs to go through mitosis before it can enter meiosis I. So in that case mitosis is happening with germ cells so the clause is false.
I would rephrase the sentence to be
The general principle is that meiosis creates only germ cells with the possibility of a decrease in chromosome number, while mitosis can create both somatic and germ cells while the ploidy stays constant.
Ok, not perfect.
How would you say the main general difference between mitosis and meiosis?
If the question is about the one and only most important difference between mitosis and meiosis, then the answer "meiosis reduces ploidy" is probably correct. But if the list of important differences is open, it would be critical to add that mitosis generates identical cells (identical to each other and any ancestral cells, barring rare new mutations), while meiosis generates genetic diversity by creating cells, which are all different from each other and from any ancestral cells. It does so by independent segregation of homologs and by crossingover within chromosomes.
According to all I've learned and heard, the only thing consistent about meiosis is that it reduces ploidy because homologous chromosomes are separated. (Not necessarily diploid to haploid - it can be polyploid as well, although odd ploidies usually seem to mess it up.)
Mitosis on the other hand mainly serves to separate two copies of a genome into different cells.
Meiosis is the specialized cell division that generates gametes. In
contrast to mitosis, molecular mechanisms and regulation of meiosis
are much less understood. Meiosis shares mechanisms and regulation
with mitosis in many aspects, but also has critical differences from
mitosis. This review highlights these differences between meiosis and
mitosis. Recent studies using various model systems revealed
differences in a surprisingly wide range of aspects, including
cell-cycle regulation, recombination, postrecombination events,
spindle assembly, chromosome–spindle interaction, and chromosome
segregation. Although a great degree of diversity can be found among
organisms, meiosis-specific processes, and regulation are generally