find and grep pipeline returning nothing

I have files named lect1.txt, lect2.doc, and lect3.doc.

I want to get a file which is a .txt file, and contains lect as the filename.

I tried

find *.txt | grep lect*

and it returned nothing.

but when I did

find *.txt | grep "lect*"

it returned lect1.txt.

What's the difference between these two expressions?