RAID 1+0 is mirroring and then striping. RAID 0+1 is striping then mirroring.

For example, say you have four disks, sd0, sd1, sd2, sd3. RAID 1+0 would mirror disks sd0 to sd2 and sd1 to sd3. You would then create a logical volume striping the data across the two mirrored devices.

In RAID 0+1, you would create a stripe on sd0 and sd1, a stripe on sd2 & sd3, and create a logical mirror between the two striped volumes.

RAID 1+0 and 0+1 have similar performance. However, RAID 1+0 has more sustained redundancy. In the two examples above, lets assume sd1 goes bad. In the RAID 1+0, sd0 and sd2 are still mirrored. In the RAID 0+1, you are left with no redundancy.