Nara period dress, and in particular court dress, was more distinctly Chinese in style.
By the time of the Tale of Genji, the style of clothing was subtly, but distinctly different. Men's court dress was baggier and longer, and the
eboshi caps were more stylised.
Compare:
And:
The second picture is actually of Akihito at his wedding, but the style of clothing is representative of the Heian aristocracy. Bear in mind that the pictures you often see of the Heian period are usually from the 11th-12th century, which is 300 years later than the Nara period. You'll also note that the hairstyle of the Nara lady is also more distinctly Chinese.
I believe, however, the square, box-like shoes were still in use by the Heian.