Rho-dependent termination of transcription is controlled by the rho protein which stalks behind the polymerase on the growing mRNA chain. At the end of the gene, polymerase impedes the run of guanine nucleotide on the DNA template. The protein collides with the polymerase and lets out mRNA from the transcription bubble.
Rho-independent termination of transcription is controlled by the specific type o sequences in the DNA templates. As the polymerase reaches the end of the gene that is being transcribed, it meets the region where cytosine-guanine is present abundantly, which causes an mRNA hairpin that impedes the polymerase as it begins to transcribe Adenine and thymine. Adenine and uracil are less thermostable hence core enzyme falls away.