OK, let's get this all deconflicted, and I'm going to address the general audience in this write-up.
There is a single package for ALL motherboard user memory (*) in the 3vo and it's made by Samsung (and in that regard, it's exactly like the Evo, just using a new/different package).
Once upon a time, we had chips in packages. If you've seen inside a PC, the CPU and memory (for example) were each a single chip inside each package. The black thing you can see and touch, the house for the chip in other words, is called a package. In the old days, we used the words chip and package interchangeably because there was just one chip inside each package.
And we've heard about taking like a piece of a PC motherboard with several chips, and making it all on one HUGE chip, and we call that a System on (a) Chip - SoC. That's still one (huge) chip in a single package.
There's also another level of organization: the multi-chip package - MCP. An MCP is not an SoC. An MCP is where they take more than one chip and house them in a single package. They're not a system, this is just a way to have fewer packages to deal with, for convenience and economy. Hence, the MCP at top of the diagrams on page 6 of the schematic.
In the 3vo's case, the MCP is a Samsung KMMLL000QM-B503. (No detailed data sheet online that I've found.)
ROM vs RAM vs eMMC
In the old days, we had RAM - random access memory, meaning you get to any memory bit any way you liked. We still have that.
In the old days, we had a kind of chip called ROM - read-only memory (with random access) - and the thing with ROM is it remembers when the power is off (RAM forgets when the power is off). A ROM could never be written to once burned at the factory. Then we had various programmable ROMs, where you could write to them for some limited number of times, but you could read them to your heart's content - these, we used for PC BIOS for those of you familiar with that.
Years ago, they invented a new kind of memory that they called flash memory. Any of your USB sticks or SD cards of any kind - all flash memory. If you recall, advanced smartphones, MP3 players and USB sticks all started hitting the shelves at about the same time - because of flash memory.
The thing we call ROM in modern smartphones isn't ROM at all, it just acts like ROM because it remembers when the power is off - it's been flash memory all along.
An SD card is a type of multi-media card (MMC). Recently, someone bright said - hey, we have one type of interface to the SD card and another type of interface to this stuff we're telling people is ROM, but it's all just flash memory. How about we make the ROM thingy with the same interface to simplify things? Good idea, so they did it.
And that's the eMMC flash memory aka ROM in the 3vo.
So - in that one Samsung package, there's going to 1 GB LPDDR2 RAM and 4 GB eMMC - or you can call it 1GB RAM / 4GB ROM.
(Fun fact if you've read this far. Flash memory is factory-built with one of two types of logic - NOR (not or) or NAND (not and). The flash we use in our phones is the nand logic type. So when you hear rooters talking about the NAND bootloader or making a nandroid backup of their rom - it's all about using slang for the actual type of flash memory the phones have.)
btw - LPDDR2 RAM and LPDDR2 SDRAM are the same thing, call it either way you like, I chose the former because it's 2 fewer characters to type.
(*) in addition to motherboard memory, you can add up to 32 GB of user storage on a microSD card.
