Gear Mfg. Co., 723 F.2d 944, 946 (D.C.Cir.1983). Res judicata has two distinct aspects'— claim preclusion and issue preclusion (commonly known as collateral estoppel) — that apply in different circumstances and with different consequences to the litigants. NextWave Pers. Commc’ns, Inc. v. Fed. Commc’ns Comm’n, 254 F.3d 130, 143 (D.C.Cir.2001); Novak v. World Bank, 703 F.2d 1305, 1309 (D.C.Cir.1983). Under claim preclusion, “a final judgment on the merits of an action precludes the parties or their privies from relitigating issues that were or could have been raised in that action.” Drake v. Fed. Aviation Admin., 291 F.3d 59, 66 (D.C.Cir.2002) (quoting Allen v. McCurry, 449 U.S. 90, 94, 101 S.Ct. 411, 66 L.Ed.2d 308 (1980)); see Page v. United States, 729 F.2d 818, 820 (D.C.Cir.1984) (<HOLDING>) (quoting Expert Elec., Inc. v. Levine, 554
holding that a claim is barred by res judicata if it arises out of the same nucleus of operative facts as the prior claim recognizing that when a cause of action is reduced to a judgment the cause of action is merged into the judgment and thereafter only an action on the judgment exists holding that a valid final judgment rendered upon the merits bars all subsequent actions based upon any claim arising out of the transaction or occurrence that was the subject matter of the previous action holding that res judicata applies when the parties are identical or in privity the first suit proceeded to a final judgment on the merits and the second claim is based on the same set of transactional facts as the first holding that final judgment on the merits in one action bars any further claim based on the same nucleus of facts for it is the facts surrounding the transaction or occurrence which operate to constitute the cause of action not the legal theory upon which a litigant relies 