Among the main differences between urine and blood pregnancy tests, apart from the fluid used to detect the hCG hormone (urine or blood), is their different sensitivity.
Sensitivity is a term that refers to the minimum value of hCG hormone that the test can detect. Therefore, more sensitive pregnancy tests will be able to detect smaller amounts of hormone than tests with a lower sensitivity. Generally, blood pregnancy tests have a higher sensitivity than urine pregnancy tests.
On the other hand, blood pregnancy tests can be qualitative or quantitative (providing the exact level of hCG hormone), whereas urine pregnancy tests are only qualitative.