Guardant (blood only) is just looking for mutated DNA in your blood. It reports mutation types and tumor mutational burden, but does not discriminate by tumor origin.

Signatera (blood) reports only the number of DNA molecules in your blood matching the DNA from your original tumor tissue, but doesn't tell you anything about mutations.

Tempus NGS (Next-generation sequencing) can tell you about mutations in the original tumor tissue.

My original Guardant test reported the ATM mutation. My second Guardant test detected that plus the CHEK2 mutation.

My Tempus test reported ATM and KRAS G12D, but not CHEK 2.