grep1-1  Exercise 2: Three Ways to Find 3.1.4
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cat > releases.txt <<'EOF'
3.1.4
3x1x4
3.1.4-beta
v3.1.4
31.14
EOF

echo "plain: grep '3.1.4'"
grep '3.1.4' releases.txt
echo
echo "fixed string: grep -F '3.1.4'"
grep -F '3.1.4' releases.txt
echo
echo "fixed string, whole line: grep -Fx '3.1.4'"
grep -Fx '3.1.4' releases.txt

Output:

plain: grep '3.1.4'
3.1.4
3x1x4
3.1.4-beta
v3.1.4

fixed string: grep -F '3.1.4'
3.1.4
3.1.4-beta
v3.1.4

fixed string, whole line: grep -Fx '3.1.4'
3.1.4

WHY THIS WORKS AS AN ANSWER
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Plain: each dot means 'any one character', so 3x1x4 matches too (x stands for the dots), and 3.1.4-beta and v3.1.4 match because the pattern may appear anywhere in the line.
31.14 does not match: it has no 3, any, 1, any, 4 in a row.
-F turns the dots into plain dots, which removes 3x1x4 but keeps the longer lines that contain 3.1.4.
-Fx demands that the whole line be exactly 3.1.4, which leaves one line. Which of the three is right depends on what you meant by 'version 3.1.4'; the point is to choose, not to take whatever the default gives you.