The 38F bra has a bigger band than the 38GG bra. The 38GG bra has bigger cups and they are a lot deeper and wider than the 38F bra.
Pictures for 38FF - Cleo » Marcie Balconnet Bra (6831)
Comparing a 32F Cleo Marcie Balconnet Bra (6831) with a 30G Claudette Dessous Mesh Underwire Bra (CD2000)
28H - Cleo » Marcie Balconnet Bra (6831)
Cup and band way too small 38E - Cleo » Marcie Balconnet Bra (6831)
Comparing a 38F Claudette Dessous Mesh Underwire Bra (CD2000) with a 38GG Cleo Marcie Balconnet Bra (6831)
Cup and band way too small 38E - Cleo » Marcie Balconnet Bra (6831)
Cleo By Panache Marcie Balconette Wired Bra 6831 RRP £29.00
Comparing a 38GG Panache Envy Balconnet Bra (7285) with a 38G Cleo
Cleo Women's Marcie Balconnet Bra, Nude, 34D