How would the Norman Infantry have differed from that of the Saxons at Hastings?

[eques]

If at all.

Would they have been mainly shieldwall?

[aligern]

Are we including missilemen? If so the Normans have more bowmen and very likely some crossbowmen. 
If we are thinking close order troops, then the biggest difference is that on the day, the English are all dismounted and so the well-equipped, wealthy warriors are in their front ranks, including the Earls and their bodyguards and the thegns and well-armoured five-hide men. The Nirman and allied French infantry were a social grade down unless there were milites (proto knights) dismounted with them. That depends on whether William had brought enough horses for all the mounted men in his army.  It is possible that some of the mercenary troops that William hired were spearmen and these might have better armour than the average infantryman. A reference in Anna Comnena to Robert Guiscard's Italo-Norman army has him levying, training and armouring footsoldiers so it is possible that more spearman were armoured.  Potential differences are in the use of javelins and of Danish axes. English troops are shown on the Tapestry with bundles of javelins (and the poorer ones with stone hammers as clubs or thrown weapons) Its possible that the Norman infantry had such short range missile weapons, but then the English had a defensive, elevated position and likely had brought more things to chuck than the Normans advancing up a hill. The Danish axes were used by the English and possibly by a group of Danish mercenaries in their ranks.  I suggest that the axes were used, teamed with spearmen who would stop advancing Norman cavalry, when the axeman would step forward and attack the stalked horse. I rather doubt that the Norman foot would include sufficient numbers of axemen to be significant, though again its possible that they had mixed spears and polearms. 
Lastly, the other big difference is that the English included numbers of ill-armed and inexperienced locals, toting, for example, those stone-headed hammers. It is very unlikely that William would bring such unarmed men across the Channel so everyone would have the basic kit, even if not a coat of expensive mail.
Roy

[Edit: tidied up typos for clarity]

[Erpingham]

Very thorough reply by Roy there.  We don't know a lot about the Norman infantry at Hastings - nobody seems to have bothered to record them much.  Archers were clearly important - the nature of the battle guaranteed them a key role - but the infantry sprearmen are a bit of an unknown.  If we hold they were professional infantry, they could have been well kitted out, as they might be if they were lesser milites whose horses weren't transported with them.  There is no reason to believe they were anything but close-order spearmen with big shields - shieldwall types as suggested.  How they compared in combat ability with the Anglo-Danish army is a bit speculative as we don't know who they were.  I doubt they had the experience or the unit cohesion of any of the housecarl units but may have been on a par with the better fyrdmen.