Can anyone explain the large variation between Commsec screen...

Can anyone explain the large variation between Commsec screen and IRESS screen buyer depth. This is without the MIX. in particular the much larger 23.5, 23 numbers ordered on IRESS.

	Column 1	Column 2	Column 3	Column 4	Column 5	Column 6	Column 7	Column 8
0	{colgroup}
1	{col=span:8	64x@}{/col}
2	{/colgroup}
3	DS	#	Bid Volume	Bid	Ask	Ask Volume	#	DS
4	TM[/COLOR][/FONT][/SIZE]	1	8,000	25	23.5	7,350	2	TM
5	TM[/COLOR][/FONT][/SIZE]	2	6,571	24.5	24.5	307,028	8	TM
6	TM[/COLOR][/FONT][/SIZE]	2	10,054	24	25	360,000	6	TM
7	TM[/COLOR][/FONT][/SIZE]	4	84,681	23.5	25.5	240,000	8	TM
8	TM[/COLOR][/FONT][/SIZE]	25	1,265,094	23	26	463,600	10	TM
9	TM[/COLOR][/FONT][/SIZE]	18	883,200	22.5	26.5	116,000	2	TM
10	TM[/COLOR][/FONT][/SIZE]	22	594,952	22	27.5	214,100	10	TM
11	TM[/COLOR][/FONT][/SIZE]	8	273,022	21.5	28	71,600	4	TM
12	TM[/COLOR][/FONT][/SIZE]	14	214,840	21	28.5	74,000	4	TM
13	TM[/COLOR][/FONT][/SIZE]	10	418,672	20.5	29	101,100	6	TM
14	TM[/COLOR][/FONT][/SIZE]	30	505,908	20	29.5	115,888	6	TM
15	TM[/COLOR][/FONT][/SIZE]	2	10,256	19.5	30	92,000	4	TM
16	TM[/COLOR][/FONT][/SIZE]	4	210,526	19	31	6,600	2	TM
17	TM[/COLOR][/FONT][/SIZE]	2	60,000	18.5	31.5	20,000	2	TM
18	TM[/COLOR][/FONT][/SIZE]	4	240,000	18	32	80,000	4	TM
19	TM[/COLOR][/FONT][/SIZE]	2	11,200	17.5	32.5	87,140	4	TM
20	TM[/COLOR][/FONT][/SIZE]	2	60,000	17	33	46,000	4	TM
21	TM[/COLOR][/FONT][/SIZE]	2	40,000	14	34	359,238	10	TM
22	TM[/COLOR][/FONT][/SIZE]	2	20,000	10	34.5	80,000	2	TM
23	TM[/COLOR][/FONT][/SIZE]	2	17,776	8.5	35	945,970	10	TM
24		-	-	-	35.5	27,250	4	TM
25		-	-	-	36	149,934	9	TM