Finally a question about Brezhnev!
In practice Brezhnev would have had less power that Stalin did. Based on offices held, in 1947 Stalin was essentially 'in charge' of the party (in his role as General Secretary) and the state (as Chairman of the Council of Peoples Commissars, then the Council of Ministers 1941-1953)... which pretty much made Stalin boss of everything important. Brezhnev was the General Secretary, but the leading role in government went to Alexei Kosygin. Brezhnev was instead head of the Presidium of the Supreme Soviet - which was more of a formal head of state role than an actual position of power in the Soviet Union, the Supreme Soviet was a sort of parliament/congress but didn't possess much power compared to the actual organs of the party and state.
The other consideration is that Brezhnev basically didn't have a free hand to do as he pleased as compared to Stalin. Brezhnev came to power as a replacement to Khrushchev and it seems pretty likely the deal was that the party-state would get a nice sedate leader who didn't mess around with everything all the time. So Brezhnev came to power with a precedent being set that his position was no longer above reproach. Brezhnev's collegues in the party had a bit more independence during this period. So without getting too carried away - Brezhnev was in a situation where he could have been removed (a practical brake on power) and kind of lacked a mandate to throw his weight around (a less concrete but never the less important barrier). This greater level of compromise is probably part of the reason Brezhnev wasn't in charge of government - no one saw fit for him to have that much power.
Compare this to Stalin, who at the height of his power could reasonably say everyone in the upper echelons owed him something for their position. For example, before assuming control of the state himself, Stalin could be happy knowing Molotov was sitting in the chair instead. Any major opposition, potential or otherwise, was pretty well smashed. The political culture was that opposition to the party was absolutely not accepted, and what constituted opposition could be pretty broad which had an impact on internal debate. Even in terms of the spirit of the era Stalin was riding pretty high - in 1947 Stalin is the leader who won WWII for the Soviets, who could oppose someone with that kind of weight? So Stalin could throw his weight around as he chose. I should emphasise that Stalin often didn't do so - his style was typically more hands off, but he had final say and if he changed course, everyone had to follow.
In terms of sources I'm always a bit reluctant with the Brezhnev era. I like to point to one or two good texts with specific reason, rather than just dump a list... but I'm not convinced the 'definitive' text on Brezhnev's era has been written. Brezhnev Reconsidered (editted by Edwin and Sandle IIRC) is probably a decent one stop shop in terms of Brezhnev's style and circumstances. But on the down side each chapter isn't huge and it covers a lot of ground so you won't get a heap of depth. I could probably give you a list of more contemporary analyses that go into more detail if you like? You can sort of piece together a better picture from those.
Sources for Stalin:
Robert Service's biography of Stalin covers the post-WWII era quite nicely, particularly the power politics. Simon Sebag Montefiore's biography is also decent and a bit more accessible.
For a more in depth discussion of the climate against anything that could be interpreted as opposition The Road to Terror by J. Arch Getty is good, nicely captures the 'culture' element, the language involved etc.
Let me know if you want me to elaborate.