2b) Ferns

3 Different Sori Arrangements:

Here are some differences between ferns and fern allies:

• Ferns tend to have megaphylls while fern allies tend to have microphylls.
• Ferns have sori with sporangiums, while fern allies have strobili, cones made up of microphylls. 
• Ferns have large frond size but fern allies have small frond size.