The difference is the contact area gold plating thickness and plating on carrier area of reel.
Part number : Contact area Carrier area
DF11-2428SCFA : 0.2μm gold Nickel
DF11-2428SCFA(04) : 0.2μm gold Tin
DF11-2428SCFB(03) : 0.3μm gold Nickel
DF11-2428SCFA(04) is VA version and our standard.