1746, 14 000 men went to battle.  Not really Scottish vs English; at least half of the "English" army were Scots, and the Jacobites were reinforced with French, Irish and English volunteers or deserters.  The Jacobite army was always meant to be an international force, with the bulk being French but the army ships were turned back by bad weather and the Royal Navy so that Charles landed virtually alone.  The Highlanders themselves were a mixed bag of clans, with some chiefs bringing only 20-30 men, often conscripted else threatened with their homes being burned.  Were they good soldiers?  They were probably fit and good with weapons, but actual clan warfare had died out more than 50 years previously. 

There was even a bunch of 180 tradesmen and apprentices from Manchester, brought up by an English ex-officer of the French army!  Nearly all executed by the government, as an example.

The Lowland Scots, many of whom were recruited from Edinburgh, did not wear tartan and carried muskets; hardly the savage Highlander. 

So the Jacobites fought for the divine right of kings and a Stuart on the throne, others for their religion, yet others to destroy the 1707 Union of the Crowns.  And of course, many were there because they were poor and had been sold into the army or else on the run from debt and scandal…