Typically Charter will offer low pay, older equipment and on-call scheduling, with a lot of pop-up trips. Pay is typically far less than Corporate pay, and usually in the range of Fractional pay. Upgrades depend on the company, sometimes seniority, sometimes performance. Charter is in the business of making money with the aircraft, they typically do not equip the aircraft with any more "bells & whistles" than they are required to.
Fractional typically flies newer equipment, has a set schedule i.e. 6 on, 4 off or something like that) but you end up commuting nearly every trip to meet the plane somewhere. The pay isn't usually much above charter. I had lunch with a 5 year NetJets Citation X Captain about a year ago and he was barely making $50k. New hires at NetJets start somewhere around $28,000-$30,000. Upgrades are typically all based on seniority.
Corporate typically flies top of the line equipment, the companies will typically equip their aircraft with all the latest equipment (HUD's, EVS, EGPWS, etc...) The pay is general the highest of the 3 (for example, at my company, new hires start first year in the $80,000 range with full benefits, pension, profit sharing, bonus, stock purchase plans, 401k, etc...). Our trips are all generally scheduled 2-6 weeks in advance, and we very rarely have a pop-up type trip, if you get called short notice it is usually because another pilot called in sick. In 7 years I have had 5 "pop-up" calls. Upgrades are generally based on performance, not seniority.
Corporate jobs can vary greatly from company to company. Just like there are good and bad airline jobs, there are also good and bad Corporate jobs.
Hope this helps...