Basically Khrushchev's economic changes related to increasing regionalisation of the economy. I say basically because Khrushchev tended to shake things up on a regular basis in his later years, and in his early years his was still working with the system he inherited. So for example the republics got a little bit more control over industry on their soil, and attempts were made to integrate enterprises in a geographic area into a collective management (sovnarkhozy). A semi-related phenomena was the move to split the party into 'industrial' and 'agricultural' wings - which sort of reflects the idea that rural and urban areas had different needs etc. and hence might need to be run and represented separately.

The Brezhnev era is a bit more complicated to interpret, in part because it is hard to see the 'grand plan' in some of the changes made, some of which were seemingly contradictory. Some sources attribute a lot of changes brought in during the late 1960s are being driven by Kosygin, and in that narrative Kosygin was more 'liberal' economically, and defeated/silienced. Complicating the 'Kosygin reforms' narrative is that many of those initiatives started in the Khrushchev era, but expanded under Brezhnev. Add to this that a lot of 'experiments' in the economy of varying scales were played with and repeated in the Brezhnev era, and it isn't always clear whether these were serious, a product of internal politics or what have you.

As a general comment I would say in the Brezhnev era, the greater emphasis was on empowering (and increasing the responsibility of) the individual enterprise. So a lot of enterprises were placed on what was called 'self accounting' (khozrachet) - basically they took care of their own finances instead of spending what they were directed to, which in some variations gave then capacity to spend the money on bonuses for employees, or to invest back into the enterprise. Later you see the integration of enterprises to create what were essentially conglomerates (so vertical integration of production, or having a bunch of steel mills become one big company instead of several), I'm having a mental blank on the name given to these groups [EDIT -found the term used for these blocs - ob'edineniye].

Conversely the Brezhnev era also saw the ministries re-assert themselves, Khrushchev's regional economic model was of course broken up and the industries were 'returned' to the ministries for management. Some experiments with inter-ministerial groups/enterprise blocs were attempted - among other problems spliting economic activity between the ministries didn't always result in a neat split of responsibility - those steel mills for example have inputs made by other ministries and they have their own ideas as to what they should do with them. The re-assertion of ministrial authority and the greater emphasis on enterprise self management is the sort of contradiction I was talking about.

Soviet plans/experiments with the use of computers in the management of the economy highlight the distinct style. The Khrushchev era favoured a model with regional computation centres, shared between local enterprises. The Brezhnev era favoured a system that would integrate enterprises and the various braches of the ministries more efficiently.

One thing both Brezhnev and Khrushchev had in common was a greater emphasis on consumer goods. The Stalin years were all about growing industrial capacity. Khrushchev and Brezhnev placed a bit more emphasis on producing things the average citizen could buy and related industries. Some contemporary authors suggest Brezhnev put a bit more emphasis on food and such and opposed to more 'industrial' consumer goods (like cars or TVs), but I think over the span of the Brezhnev years it sort of balanced out.

Both also placed progressively less emphasis on central planning, with varying approaches to achieving this. Lots of experiments with changed pricing and allocation mechanisms, letting enterprises establish their own links with distributors and so on.