The 30F bra has a bigger band than the 28G bra. The 28G bra has deeper cups than the 30F bra, but they are about the same width.
Comparing a 28G Freya Deco Moulded Plunge Bra (4234) with a 30F
Bras I Hate & Love: What Freya Has To Offer (Brand Overview)
28E - Freya » Deco Moulded Plunge Bra (4234)
Deco Underwire Plunge T-Shirt Bra
Description Uses the UK sizing system. This brand starts with a D cup in most styles, then continues D, DD, E, F, etc. up to a UK K cup. Visit our FAQ
Freya Deco Underwire Molded Strapless Bra in Nude
30E - Freya » Deco Moulded Plunge Bra (4234)
Why can't I find pretty bras in my size?'' If you've ever asked yourself that question, here's the one-word answer: Freya. Freya offers pretty full
Deco Plunge T-Shirt Bra
Gapping because cup size, band size, or both? 30F - Freya » Deco
Freya Tailored Molded Plunge Underwire T-Shirt Bra (401131),28D
Freya Womens Deco Underwire Moulded Plunge Bra
Freya Womens Deco Underwire Moulded Plunge Bra, 28DD, Nude