Roxio disc burning software sees 4.7 GB DVD capacity as 4.38 GB only.
This is due to the differences between Binary and Decimal notation used by software developers on one hand and the manufacturers on the other.
This is simply due to differences in Binary versus decimal notation.
There is 1024 bytes in a kilobyte, and this is a fact.
However, manufacturers quote disc capacity in decimal notation. For example, single-layer DVD discs are said to have a capacity of "4.7 GB". Yes these discs actually stores 4,700,000,000 bytes (give or take a few), but when you translate this to the actual binary notation used for storage, it is a different story. Using traditional binary notation, that disc has a capacity of 4,700,000,000 bytes, which when divided by 1024 will equal to 4,589,843.75 KB. This divided by 1024 = 4,482.269+ MB, and then divided by 1024 = 4.377+ GB, which is often rounded to 4.4 GB.
The "4.7 GB" is a marketing label manufacturers use to represent their DVD disc capacity; pretty much like the "4K" label used for UltraHD TVs. This isn't really 4K, since most (if not all) TVs that use this label have a resolution of 3,840x2160 only. True 4K has a resolution of 4,096x2160.