There are some differences as explained in EE-261 "ADSP-BF537 Blackfin
Highlights for ADSP-BF533 Users". Excerpt from EE-261 Boot Rom section:
"ADSP-BF533 processors have two BMODE pins. ADSP-BF537 processors have three
pins, enabling additional boot modes as shown in Table 1.
ADSP-BF537 processors have 2 Kbytes of onchip Boot ROM - twice the amount
available on ADSP-BF533 parts. The Boot ROM not only provides new boot modes,
but also provides enhanced features."
For more details, please refer to EE-261 (www.analog.com/ee-notes).