I'll throw in what I know to help muddy the waters

concentrating on
Ontario/Quebec which are most familiar, and skip over low-band (bad
pun?)
138-144MHz is used by all levels of gov't (federal/provincial/municipal)
plus some commercial use including pesky pagers. There is no universal
repeater spacing although -4.020 (Ont) and -3.990 (Que.) are common
for outputs in the 142-144 range. Some 143MHz repeaters have inputs
in the 148MHz range. Municipal PDs were very heavy in this area before
800MHz trunking came along.
148-160MHz takes in a mix of government, military and commercial.
160-162MHz (roughly) is similar to U.S. with rail and marine. 162-174
is primarily commercial (unlike the U.S. which I believe is exclusively gov't),
with some gov't and military.
406-420 is primarily gov't services (all levels) with some commercial
use including links (most 414/419MHz) which includes pager links. In
Quebec, this band is favoured for municipal police and fire (although they
also use the 150MHz bands). Police MDTs used to hang out around
406-409 and some may still.
420-421 is paired with 409-410 and traditionally used for links, including
rural radio-telephone links in (relatively) remote areas such as Manitoulin
Island; but recently has seen new trunking assignments. There is some FD
and PD in here. I can pick up a link to the local weather TX on 420.0500 .
421-422 as previously mentioned seems to be mostly RCMP and CSIS;
inputs +5 (and reportedly +4MHz in some cases). They have some above
that but 422-425 is primarily commercial (including trunking). 422MHz is where
one of the first trunked systems in Ottawa showed up (GE Marc-V) over
20 years back. Currently there's MPT-1327 in the Quinte area (Belleville) and
LTR/Passport etc. from the Montreal area.
450-451 and 455-456 are broadcast link sub-bands similar to the U.S.
The rest of the band is commercial. PD, FD, and gov't services don't use
the 453/460MHz bands as south of the border, maybe with the odd
exception (they use 406-420). Repeater sub-bands are 451-455 and
460-465 with +5.0000, +4.9875, or +5.0125MHz spacing. Simplex use
varies but in my area it is primarily 453/458MHz and 464/469MHz channels.
There is no UHF "T-band" in Canada; 470-512 is still TV broadcast.
851-869 usage is similar to the U.S.; a mix of commercial and gov't.
Standard -45MHz spacing applies.
902-928 is of course the "ISM band" packed with such Industrial/Scientific/
Medical devices (right!) as cordless phones, baby monitors, intercoms, and
wireless head- phones, but it's also a radiolocation band. Transit it Ottawa
(OC Transpo) is licensed for a fixed-signpost/proximity type of VLS on some
oddball frequencies; mildly interesting but not much fun to listen to.
928-932 is paired with 952-956 for non-voice point-multipoint systems
including hydro/water SCADA, telemetry, traffic light control, and my
favourite, high-powered pagers (up to a kW or more).
932-935 is paired with 941-944 for links. Some of these are digital/
multi-channel between trunked sites. OPP used a few 932/941Mhz pairs
on their old system.
935-940MHz is for trunking (-39MHz spacing) as in the U.S.. Mobitex seems
to hang out in the 938-940MHz part although not exclusively. There's also
the rail data system (ATCS) in the high 935MHz range. I've heard U.S.
mobitex in this range also (935.8625).
Last I heard, 944-948 and 948-952MHz were assigned to low-power
digital indoor phone systems using CT2+ standard. Canadian Tire and some
other large retailers use this (Nortel Companion system, typ.). It's TDD
(ping-pong) with TX and RX on the same frequencies. All digital and 17mW
maximum power even for the base stations. There may be other uses
though.
STL's occupy 956-960MHz.
And.... that's about as high up the spectrum as I go!
Dave