Abrams was designed in 1972–1975, Leopard 2 in 1970s. Only Challenger 2 is newer, designed in 1986–1993. Hence the basic models are not very new. Challenger 3 and Abrams X are coming.
Parts that have received significant upgrades later probably can be swapped for older versions even without talking too much. From that is known, Abrams will be without depleted uranium in the armor.