P & L retained profit
On the profit an loss account, the retained profit is the profit that is left in a company after paying out dividends: post tax profit less dividends paid.
Balance sheet retained profit.
Retained profit on the balance sheet is the accumulated retained profit. In each accounting period it is increased by the P & L retained profit for that period.
Retained profit on the balance sheet is significant because dividends must be paid out of distributable reserves, this means that a low accumulated retained profit limits dividend payments. This is why scrip issues are taken to be signs of confidence: management are signalling that there is no danger that reducing distributable reserves will make a dividend cut necessary. There is plenty of money to pay dividends.
A paradoxically different inference is that high distributable reserves are a sign of financial stability: high retained earnings are an indicator of a history of profitability. For this reason, balance sheet retained earnings is a factor in the Altman Z-score.