Both FSH and LH are indirectly involved in endometrial thickening:
- GnRH regulates release of the gonadotropins- luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from specialized cells (gonadotropes) in the anterior pituitary gland
- LH and FSH promote ovulation and stimulate secretion of the sex hormones estradiol (and estrogen) and progesterone from the ovaries.
- As estradiol levels increase, the intact basal layer regenerates the endometrium to its maximum thickness late in the ovarian follicular phase (proliferative phase of the endometrial cycle). ...{1}
Again, wikipedia{2} says the same:
...In both cases, the endometrium initially proliferates under the influence of estrogen.
The difference between the hormones, of course lies in their other functions. You can see this for more on that. To clarify again, the endometrium does not thicken 'differently' under the influence of each.
{1}-https://www.msdmanuals.com/professional/gynecology-and-obstetrics/female-reproductive-endocrinology/female-reproductive-endocrinology?query=lh
{2}-https://en.wikipedia.org/wiki/Endometrium#Cycle