Are these two cars the same? l know the Lexus IS series is called Toyota Altezza in other countries, so what about these two?

Yes, the only difference is the location of the steering wheel as they are built for different markets (Lexus is for U.S. and Europe, the Toyota is for Japan). Lexus did not reach the Japanese market until 2005, which is why some Lexus models as badged as Toyotas.

yes same things. In the US the SC300 came with a 2jzge (same as NA Supra MKIV) and SC400 came with the 1UZFE v8. In Japan the Soarer came with a 1JZGTE and also a 1UZFE. It is the same car but like mentioned, the soarer is RHD.