A: TextLink

Built as a bulk outreach campaign tool — basically a lightweight SMS marketing platform.

Your Android phone becomes the SMS gateway controlled through a web app.

Designed for sending batch texts quickly to lists (CSV import, campaigns, scheduling).

TextBee

Essentially an SMS gateway API — turns your Android into a programmable SMS server.

More technical: intended for apps / developers to integrate SMS sending into systems, not for non-technical marketing campaigns.

Bottom line:
TextLink = SMS outreach tool; TextBee = SMS gateway engine.