Technical and specific terms explanation.

MicroEJ Application: A MicroEJ Application is a software program that runs on a MicroEJ-ready device. A MicroEJ Application is called a MicroEJ Standalone Application or a MicroEJ Sandboxed Application depending the way it is linked.
MicroEJ Standalone Application: MicroEJ Standalone Application is a MicroEJ Application that is directly linked to the C code to produce a Single-App Firmware.
MicroEJ Sandboxed Application: A MicroEJ Sandboxed Application is a MicroEJ Application that can run over a Multi-Sandbox Firmware. It can be linked either statically or dynamically. When statically linked, it is called a Resident Application, as it is part of the initial image and cannot be removed.
MicroEJ Foundation Libraries: A MicroEJ Foundation Library is a MicroEJ library that provides core runtime APIs or hardware-dependent functionality. It is often connected to underlying C low-level APIs.
MicroEJ Add-On Libraries: A MicroEJ Add-On Library is a pure Java library that is implemented on top of one or more MicroEJ Foundation Libraries.
MicroEJ Virtual Device: A MicroEJ Virtual Device is a software package that includes the similar of a MicroEJ-ready device (Runtime, Libraries and Resident Applications) for testing a MicroEJ Sandboxed Application in MicroEJ Studio. Virtual devices can be downloaded here.
MicroEJ Virtual Device Player: A MicroEJ Virtual Device Player is a software package that includes the simulation part of a MicroEJ Platform and a MicroEJ Standalone Application that can be run on any PC without the need of MicroEJ Studio.
MicroEJ SDK: MicroEJ SDK allows firmware developers to build a MicroEJ-ready device, by integrating a MicroEJ Architecture with both Java and C software on their device.
MicroEJ Studio: MicroEJ Studio allows application developers to write a MicroEJ Sandboxed Application, run it on a Virtual Device, deploy it on a MicroEJ-ready device, and publish it to a MicroEJ Store.
MicroEJ Forge: MicroEJ Forge provides Cloud-based services to publish, host and deploy MicroEJ Applications and Firmware to MicroEJ-ready devices. MicroEJ Forge allows OEMs to manage users, expose devices, distribute and monetize applications. It manages customers’ accounts credentials.

MicroEJ Architecture: A MicroEJ Architecture is a software package that includes the MicroEJ Runtime port to a target instruction set and a C compiler, and MicroEJ Foundation Libraries.
MicroEJ Platform: A MicroEJ Platform is a software package includes the build of a C board support package (BSP, with or without RTOS), a MicroEJ Architecture, adaptation layers, the MicroEJ Simulator and its associated MicroEJ Mocks.
MicroEJ Platform Reference Implementation: A MicroEJ Platform Reference Implementation is a software package that includes all source material to be able to build a MicroEJ Platform on a target device. A MicroEJ Platform Reference Implementation allow device software developers to bring-up and derive a MicroEJ Platform on their custom board.
MicroEJ Firmware: A MicroEJ Firmware is the result of the binary link of a MicroEJ Standalone Application with a MicroEJ Platform.
MicroEJ Mono-Sandbox Firmware: A MicroEJ Mono-Sandbox Firmware is a MicroEJ Firmware that implements an unmodifiable set of functions. (previously MicroEJ Single-app Firmware)
MicroEJ Multi-Sandbox Firmware: A MicroEJ Multi-Sandbox Firmware is a MicroEJ Firmware that implements the ability to be extended, by exposing a set of APIs and a memory space to link MicroEJ Sandboxed Applications. (previously MicroEJ Multi-app Firmware)
MicroEJ Firmware Architecture:

MicroEJ Simulator: MicroEJ Simulator allows running MicroEJ Applications on a target hardware simulator on the developer’s desktop computer. The MicroEJ Simulator runs one or more MicroEJ mock that mimics the hardware functionality. It enables developers to develop their MicroEJ Applicaitons without the need of hardware.
MicroEJ Mock: A MicroEJ Mock is a mockup of a Board Support Package capability that mimics an hardware functionality for the MicroEJ Simulator.