If an agreement to sell goods is broken by the seller, as the property in the goods has not passed to the buyer, the buyer has only personal remedies against the seller. See chapter 8, where the buyer's remedies by way of action for damages or action for specific performance are discussed. In the case of a sale, however, if the seller breaks his engagement to deliver the goods, then, as the property in the goods has passed to the buyer, the buyer has not only personal remedies against the seller, but has also the usual proprietary remedies in respect of the goods themselves, such as the actions for conversion and detinue.
See 25 Halsbury, Laws of England, p. 118, referring, as to detinue, to Langton v. Higgins, 1859, 4 H. & N. 402, and, as to conversion, to Chinery v. Viall, 1860, 5 H. & N. 288; cf. Hollins v. Fowler, 1875, L.R. 7 H.L. 757, 2 R.C. 410; Consolidated Co. v. Curtis,  1 Q. B. 495, 25 R.C. 161; see also title Trover and Detinue, 27 Halsbury, Laws of England, pp. 887 ff.; McGregor v' Whalen, 1914, 31 O.L.R. 543, 20 D.L.R. 489.
In the United States the Uniform Sales Act provides 66. Where the property in the goods has passed to the buyer and the seller wrongfully neglects or refuses to deliver the goods, the buyer may maintain any action allowed by law to the owner of goods of similar kind when wrongfully converted or withheld.