Samsung has decided to re-brand its Exynos 5433 processor as the Exynos 7 Octa. This is the chip that powers the new Samsung Galaxy Note 4, depending upon your region. It appears that Samsung thought the 64-bit capable ARM v8 20nm Exynos 5433 deserved a snappier, shorter and more distinctive name.
The new Samsung Exynos 7 Octa name will help in differentiating the processor from the rest of the Exynos 5XXX range. Perhaps Samsung should have thought about this before as the Exynos 5433 (from now on referred to as the Exynos 7 Octa) does indeed stand out from other 5XXX parts in its performance stats.
The Exynos 7 Octa is a big.LITTLE (ARM Cortex-A57 cores and ARM Cortex-A53 cores) Heterogeneous Multi Processing (HMP) chip which "provides a 57 per cent CPU performance increase from the previous generation Exynos 5 Octa". It is Samsung's first 64-bit ARM v8 chip and offers a substantial performance boost over the previous generation Exynos 5 Octa chipset while consuming less battery power, thanks to its 20nm HKMG manufacturing process. In graphics performance the Exynos 7 Octa is also a step above Exynos 5XXX chips as it uses the Mali-T760 which, according to Samsung, provides "74% enhanced graphics performance".
Some possible explanations of the name change are put forward over at Tom's Hardware. One theory is that the 64-bit mode of this ARM v8 chip wouldn't be supported on KitKat without serious efforts from Samsung's software developers. So as Android Lollipop approached it is thought that Samsung just waited for the new mobile OS to come along before this rebrand and 64-bit capability was highlighted. It is also thought that Samsung didn't want to create confusion with a 32-bit Qualcomm Snapdragon 805 SoC and a 64-bit Exynos in the Note 4 being available so disabled the 64-bit mode of its own processor. With Lollipop arriving on the Note 4 it is unclear whether 64-bit mode will be enabled or just be left as a headlining Galaxy Note 5 feature.