Answer:
Harriet Tubman (1822-1913) and Frederick Douglas (1818-1895) were abolitionists.
Tubman had been working secretly (and also as a spy for the Union Army during the American Civil War) to help slaves escape to northern states (where slavery had been made illegal).
However Frederick Douglas had been working openly to end slavery through most of his life (after he escaped slavery.
Step-by-step explanation:
Harriet Tubman escaped slavery in 1849 by escaping to northern states. However in 1850, Fugitive Slave Act of 1850 was passed in most of the northern states which punished those who encouraged or assisted in escaping and forced law enforcement agencies to capture the escaped slaves and also those who assisted in escaping. Harriet Tubman had to move to farther north into British North America to escape this law. Moreover she had to make many visit to southern states to help escape her family and other slaves. All this meant she had to work very privately during her efforts to end slavery.
Fredrick Douglas who was an abolitionist and a public orator had escaped slavery from southern states in 1838, and by 1850's Fugitive Slave Act had already established himself as a free man and a public orator. So he did not have to work secretly.
The fact that Harriet Tubman worked privately and Douglass worked openly is also clearly described in a letter from Douglas to Harriet Tubman, which reads as,
"The difference between us is very marked. Most that I have done and suffered in the service of our cause has been in public, and I have received much encouragement at every step of the way. You, on the other hand, have labored in a private way. I have wrought in the day – you in the night. ... The midnight sky and the silent stars have been the witnesses of your devotion to freedom and of your heroism"