When comparing Tessel 2 vs Rock64, the Slant community recommends Rock64 for most people. In the question“What are the best single-board computers?” Rock64 is ranked 9th while Tessel 2 is ranked 34th.
Ranked in these QuestionsQuestion Ranking
Pro NodeJS support out of the box
Out of the box it supports Node 4.x LTS and doesn't require any setup to use it.
Pro Co-processor system
Runs Linux and user application code on a 580MHz Mediatek router-on-a-chip, with an asynchronous 48MHz SAMD21 coprocessor for GPIO, ADC, I2C, SPI, PWM and UART programming
Pro Programmable via USB or Wifi
Pro Easy to get started with
The Tessel 2's "Getting Started" experience requires little more than installing Node.js and a single package (the CLI) via npm. Complete walkthroughs for Linux, Mac and Windows are available and up-to-date
Pro USB 3 Bus support
Pro Beats Raspberry Pi on price and performance
Pro Can have up to 4gb of low power RAM
Pro Gigabyte ethernet
Pro 4K/60h hdmi 2a
Pro Barrel power connector
More rugged connection. Less likely to be damaged.
Pro Extra Gpio pins
Pro Main header Pi 3 pin layout
Can use Pi shields.
Con Very little memory
64 megabytes of RAM. This places it more in line with an Arduino style board than a SBC on the level of Raspberry Pi.
Con Lack of support, Unstable USB 3,
Only Android with TV UI is available. It is almost unusable with a touchscreen display.
Community is somewhat helpful but is very small. The board developers do not participate in community discussions. No regular Android build available. Lack of accessories and project guidelines.
Con Power connector is not MicroUSB or MiniUSB
Can't use power banks as a power source because of that.