I would simply redirect you to this RG thread where it has been already discussed in details https://www.researchgate.net/post/What_is_the_difference_between_Hek293_and_Hek293T_cell_lines
Human Embryonic Kidney (HEK) cell line (e.g., Freestyle HEK 293F cells). These cells have been derived from the HEK 293 cell line, are adapted to grow in suspension cultures, reaching high densities using serum-free media (such as FreeStyle 293 Expression Medium).