Never had a BigBud 220 so can't answer from experience but after reading the manual for the Big Bud hear is my take. In all metal mode the 220 had a thresh hold volume/tone, manual ground balance and a toggle switch tuner. The 505 does not have thresh hold tone, it searches in silence. The Ground trac on the 505 is similar to the ground balance on the 220. The processor on the 505 automatically keeps the "thresh hold" quiet and the detector at optimum, so there is no tuner switch to re-tune the thresh hold. If you are searching in all metal mode on the 505 you do need to hit the ground trac button occasionally to make sure it is tuned to the changing ground mineralization. My 505 in all metal mode with the 4 inch coil will pick up all US coins to 8 inches, the 8 inch coil up to 10-12 inches and the 10 inch coil to 14 plus. (coin garden). While the BB220 was good in its time, the newer technology in the 505 is much better.
In disc mode the BB220 seems to operate like the auto notch feature on the 505, which is a fantastic mode to search trashy areas in. Example, yesterday I went to a local park and saw another detectorist on the beach area (fresh water). We made small talk and I learned that someone else had also been there, and that idiot did not cover his holes or take the trash he had dug off the beach. I went back later after the gentleman had left and I found 52 cents in about an hour. A quarter, 2 dimes and 7 pennies. I also dug countless pull tabs and foil cause they fall in the gold range. He had found 67 cents when we parted ways and I don't know if he found anything else after that. My point is that the 505 found 52 cents right after 2 people had already detected this area. I was using the 4 inch coil.
The 505 also has a notch mode, which the BB220 did not have, and an all metal disc mode, which is simply searching in disc mode with the disc nob turned all the way down. This is the deepest disc mode search setting. In my opinion the 505 is much better than the BB220. I have found a gold ring, several silver rings, silver locket, and lots of clad coins with my 505. It is a very good unit for the money. Hope this helps you.
capt.
