BoogeyB Hey there, welcome on our forum!
Most of the differences between the two eco systems lay in usability, which corresponds in features, but also philosophy.
The terra 4k is aimed, at the cinematographer. It gives you a multitude of sturdy mounting solutions, like PL, EF, e-mount,
all with positive lock to ensure a wiggle free sturdy solution. Also the Terra features a cinematographer minded Menu layout, with many different anamorphic desquezes, also the sensor is higher, (1.5X aspect), so if you are into anamorphic shooting you will crop more on the Blackmagic then on the Terra 4k. The terra features a possibility to add a kineback with sdi, and vlock and timecode. If you plan to do very small one man shoots, and you can carry a lot of batteries with you, and you mostly shoot on ef lenses and mft the Blackmagic might be fun, bu once you start to add monitors (kineifnity uses great monitors which connect with very sturdy lemo cable), and you need xlr audio you want to look at Kinefinity. Also media with the ssd 2.5 inch cards is super cheap on the Terra 4k. Please let us know if you have any additional questions
